Inventory system with swiveling vertically mobile drive units

ABSTRACT

Disclosed inventory systems, methods, and devices can be used to retrieve and transport resources from one location to another. Specifically, a vertically mobile drive unit including a vertical element retention mechanism can be controlled by a management component to retrieve a resource, transport the resource from one floor to a different floor in an inventory system, and deposit the resource at a destination. The vertically mobile drive unit can transit vertically along a vertically disposed element in an inventory system, such as a structural pole or column; and can rotate around the structural pole or column in order to set down on an upper level after ascending, or to clear the upper level prior to descending.

BACKGROUND

Modern inventory systems, such as those in mail order warehouses, supplychain distribution centers, airport luggage systems, and custom-ordermanufacturing facilities, face significant challenges in responding torequests for inventory items. As inventory systems grow, the challengesof simultaneously completing a large number of packing, storing, andother inventory-related tasks become non-trivial. In inventory systemstasked with responding to large numbers of diverse inventory requests,inefficient utilization of system resources, including space, equipment,and manpower, can result in lower throughput, unacceptably long responsetimes, an ever-increasing backlog of unfinished tasks, and, in general,poor system performance.

Expanding the size or capabilities of many inventory systems requiressignificant changes to existing infrastructure and equipment. As aresult, efforts are made to increase the utilization of space bounded bya finite infrastructure by increasing the density of packing in bothhorizontal and vertical directions. For example, inventory systems arenow occasionally split between ground floors and mezzanine levels withina large structure. However, moving inventory items into or out ofdensely packed storage areas or multilevel storage areas can beinefficient using existing ground-based units or conventional verticaldisplacement mechanisms like elevators.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments in accordance with the present disclosure will bedescribed with reference to the drawings, in which:

FIG. 1 illustrates an example inventory system in a side view, inaccordance with embodiments;

FIG. 2 illustrates components of an inventory system according to aparticular embodiment;

FIG. 3 illustrates in greater detail the components of an examplemanagement module that may be utilized in particular embodiments of theinventory system shown in FIG. 2;

FIGS. 4 and 5 illustrate in greater detail an example mobile drive unitthat may be utilized in particular embodiments of the inventory systemshown in FIG. 2;

FIG. 6 illustrates in greater detail an example inventory holder thatmay be utilized in particular embodiments of the inventory system shownin FIG. 2;

FIGS. 7-9 show a drive unit with a vertical element grasping mechanismfor implementing aspects of an inventory system, in accordance withembodiments;

FIG. 10 shows a second embodiment of an alternative vertical elementgrasping mechanism, in accordance with embodiments;

FIG. 11 illustrates a mode of moving a drive unit onto an upper level ofan inventory management facility;

FIG. 12 illustrates a second mode of moving a drive unit onto an upperlevel of an inventory management facility;

FIG. 13 illustrates a third a mode of moving a drive unit onto an upperlevel of an inventory management facility;

FIG. 14 illustrates a mechanism for actuating a gripping element of avertical element grasping mechanism;

FIG. 15 illustrates a fourth mode of moving a drive unit onto an upperlevel of an inventory management facility;

FIG. 16 shows a second drive unit with an internal vertical elementgrasping mechanism for implementing aspects of an inventory system, inaccordance with embodiments;

FIG. 17 shows a fifth mode of moving a drive unit onto an upper level ofan inventory management facility;

FIG. 18 shows a third drive unit with an alternative internal verticalelement grasping mechanism for implementing aspects of an inventorysystem, in accordance with embodiments;

FIG. 19 illustrates a sixth mode of moving a drive unit onto an upperlevel of an inventory management facility;

FIGS. 20-23 show various embodiments of drive elements for a verticalelement grasping mechanism, in accordance with embodiments;

FIG. 24 illustrates an example system for controlling a drive unit totransit onto an upper level of an inventory management facility by wayof a movable panel;

FIG. 25 illustrates a second example system for controlling a drive unitto transit onto an upper level of an inventory management facility byway of a movable panel;

FIG. 26 illustrates an example system for controlling a drive unit totransit from an upper level to a lower level of an inventory managementfacility by way of a movable panel;

FIG. 27 illustrates an example system for controlling a drive unit totransfer a resource to an upper level of an inventory managementfacility;

FIG. 28 illustrates an example system for controlling a drive unit withvertical element transit capability in an inventory system, inaccordance with embodiments;

FIG. 29 illustrates an example process for controlling a drive unit totransfer a resource between a lower and upper level in an inventorysystem;

FIG. 30 illustrates a second example process for controlling a driveunit to transit between a lower and upper level in an inventory system;

FIG. 31 illustrates a third example process for controlling a drive unitto transit between a lower and upper level in an inventory system;

FIG. 32 illustrates an example process for controlling a drive unit toascend to an upper level of an inventory system via a movable panel;

FIG. 33 illustrates an example process for controlling a drive unit todescend from an upper level of an inventory system via a movable panel;

FIG. 34 illustrates a second example process for controlling a driveunit to ascend to an upper level of an inventory system via a movablepanel;

FIG. 35 illustrates a second example process for controlling a driveunit to descend from an upper level of an inventory system via a movablepanel;

FIG. 36 illustrates an example process for controlling a drive unit toreposition the drive unit in an inventory system; and

FIG. 37 illustrates an environment in which various features of theinventory system can be implemented, in accordance with at least oneembodiment.

DETAILED DESCRIPTION

In the following description, various embodiments will be described. Forpurposes of explanation, specific configurations and details are setforth in order to provide a thorough understanding of the embodiments.However, it will also be apparent to one skilled in the art that theembodiments may be practiced without the specific details. Furthermore,well-known features may be omitted or simplified in order not to obscurethe embodiment being described.

Embodiments herein are directed to an inventory system having variousresources, such as inventory, containers, inventory holders, dunnage,boxes, and the like; and drive units for moving the resources.Specifically, features herein are directed to moving the resourcesbetween disparate locations in an inventory management facilityaccording to instructions from an inventory system. Disparate locationsin an inventory system may be, for example, different mezzanine levelsof a multi-level inventory management facility. To this end, theinventory system may include vertically mobile drive units for assistingin moving resources and/or inventory items between locations at onefacility level and another. The inventory system can also possessautonomous ground drive units and other robotics for transporting andprocessing resources and inventory items.

Vertically mobile drive units as described herein are capable oftransiting vertical members within the inventory system. Such driveunits are operable to transfer resources between upper and lower levelsof the inventory system within an inventory management facility, such asa warehouse, shipping center, or comparable inventory system.Specifically, embodiments are directed to vertically mobile drive unitspossessing vertical element grasping mechanisms that are operable tograsp vertical elements, such as structural columns, beams, or the like;and to transit upward or downward along the vertical elements. Accordingto various embodiments, the vertically mobile drive units can move tograsp the vertical elements, transit up or down along the verticalelements, and either depart the vertical elements at a different levelof the inventory system, or receive or offload a resource at differentlevels of the inventory system. According to some embodiments, thevertically mobile drive units are autonomous, semi-autonomous, orcomputer-controlled by way of an inventory management system thatdirects the drive units to transit throughout the inventory system andtransfer resources therein. Embodiments herein are also directed tosystems for controlling a vertically mobile drive unit in an inventorysystem, and specifically to various processes for enabling a verticallymobile drive unit to transit between destination and origin positions ina multi-level inventory system, or to transfer resources between thedestination and origin positions.

In alternate embodiments, an inventory system may operate on a singlefloor, or on any practicable number of floors including multiplemezzanine floors. For example, in some embodiments, an inventory systemmay operate on a ground floor and on two, three, four, or more than fourmezzanine floors. In some other embodiments, a ground floor may be usedfor non-storage purposes, such that an inventory system operates on one,two, three, four, or more mezzanine floors and may optionally ferryitems or containers to the ground floor

As used herein, “resource” can include any suitable object or containerto be moved within an inventory system, e.g., items of inventory,containers, packaging material, or the like. In some cases, “resource”can include any item within an inventory system that is within a weightlimit of a vertically mobile drive unit. In certain cases, “resource”can include even heavy items, in some cases includinginventory-containing totes, or in some cases including inventory holders(see FIG. 6).

By way of example, suppose that an inventory system has two levelsincluding a ground floor and a mezzanine. A resource (e.g., emptycontainers for sorting or transporting inventory) is depleted on themezzanine, and a surplus of the containers is available on the groundfloor. An inventory management system can receive a request to transferthe surplus containers from the ground floor to the mezzanine, anddispatch a vertically mobile drive unit to the location of the surplusresource (the origin). Once retrieved, the drive unit can transport itspayload from the origin to a vertical element in the inventory system(e.g., a vertical pole or column that passes near or passes through themezzanine), where the drive unit can grip the vertical element, climbvertically along the vertical element until above the mezzanine, andthen depart the vertical element to transit on the mezzanine level. Thevertically mobile drive unit can then transfer the surplus containers tothe location of the depleted resource (the destination). By transitingup to the mezzanine along a vertical element in the inventory system,the vertically mobile drive unit avoids adding traffic to any of theconventional vertical movers (e.g. elevators or the like) in theinventory system, thus improving overall efficiency of the inventorysystem.

FIG. 1 shows one such example system 100, in which a vertically mobiledrive unit 103 is shown transferring a resource 116 from a ground floor102 to a mezzanine 106, in accordance with embodiments. The drive unit103 is shown in various stages of transferring the resource 116including, receiving the resource from an origin element 614 at anorigin position 608, transiting vertically along a vertical element 604that runs adjacent to the mezzanine 106, and depositing the resource toa destination element 612 at a destination position 107. The verticallymobile drive unit 103 has a vertical element grasping mechanism 105which is operable to securely grip the vertical element 604, and toprovide sufficient vertical force to cause the drive unit to traverse upand down the vertical element. The vertical element grasping mechanism105 is also operable to transit the drive unit 103 around the verticalelement 104 when the drive unit has passed above the level of themezzanine 106 in order to place the drive unit on top of the mezzaninesuch that it can release the vertical element and transit to thedestination location 107. According to some embodiments, the verticallymobile drive unit 103 may be autonomous or semiautonomous, and receiveinstructions to transfer the resource 116 by way of an inventory systemmanagement element 109; however, in some cases, the drive unit 103 maybe operated directly under the control of the inventory systemmanagement element 109. Generally, vertically mobile drive units 103 areoperable to also navigate horizontally on a ground floor 102 ormezzanine 106, and can attach to and detach from a vertical member 104as needed to transit between floors.

Aspects of vertical element grasping mechanisms, systems, and methodsfor transiting between different levels of an inventory system arediscussed below in greater detail with reference to FIGS. 7-35.Vertically mobile drive units 103 as described herein, in addition tohaving the capability of transiting between floors along verticalelements, are operable to transit horizontally along those floors.Inventory systems, as well as systems and methods for transiting alongthe floor and for transporting items thereby, are discussed below ingreater detail with reference to FIGS. 2-6.

FIG. 2 illustrates the components of an inventory system 10. Inventorysystem 10 includes a management module 15, one or more mobile driveunits 20, one or more inventory holders 30, and one or more inventorystations 50. Mobile drive units 20 transport inventory holders 30between points within a workspace 70 in response to commandscommunicated by management module 15. Each inventory holder 30 storesone or more types of inventory items. As a result, inventory system 10is capable of moving inventory items between locations within workspace70 to facilitate the entry, processing, and/or removal of inventoryitems from inventory system 10 and the completion of other tasksinvolving inventory items or other resources.

Management module 15 assigns tasks to appropriate components ofinventory system 10 and coordinates operation of the various componentsin completing the tasks. These tasks may relate not only to the movementand processing of inventory items, but also to the management andmaintenance of the components of inventory system 10. For example,management module 15 may assign portions of workspace 70 as parkingspaces for mobile drive units 20, the scheduled recharge or replacementof mobile drive unit batteries, the storage of empty inventory holders30, or any other operations associated with the functionality supportedby inventory system 10 and its various components. Management module 15may select components of inventory system 10 to perform these tasks andcommunicate appropriate commands and/or data to the selected componentsto facilitate completion of these operations. Although shown in FIG. 2as a single, discrete component, management module 15 may representmultiple components and may represent or include portions of mobiledrive units 20 or other elements of inventory system 10. As a result,any or all of the interactions between a particular mobile drive unit 20and management module 15 that are described below may, in particularembodiments, represent peer-to-peer communication between that mobiledrive unit 20 and one or more other mobile drive units 20. Thecomponents and operation of an example embodiment of management module15 are discussed further below with respect to FIG. 3.

Mobile drive units 20 move inventory holders 30 between locations withinworkspace 70. Mobile drive units 20 may represent any devices orcomponents appropriate for use in inventory system 10 based on thecharacteristics and configuration of inventory holders 30 and/or otherelements of inventory system 10. In a particular embodiment of inventorysystem 10, mobile drive units 20 represent independent, self-powereddevices configured to freely move about workspace 70. Examples of suchinventory systems are disclosed in U.S. Pat. No. 9,087,314, issued onJul. 21, 2015, titled “SYSTEM AND METHOD FOR POSITIONING A MOBILE DRIVEUNIT” and U.S. Pat. No. 8,280,547, issued on Oct. 2, 2012, titled“METHOD AND SYSTEM FOR TRANSPORTING INVENTORY ITEMS”, the entiredisclosures of which are herein incorporated by reference. Inalternative embodiments, mobile drive units 20 represent elements of atracked inventory system configured to move inventory holder 30 alongtracks, rails, cables, crane system, or other guidance or supportelements traversing workspace 70. In such an embodiment, mobile driveunits 20 may receive power and/or support through a connection to theguidance elements, such as a powered rail. Additionally, in particularembodiments of inventory system 10 mobile drive units 20 may beconfigured to utilize alternative conveyance equipment to move withinworkspace 70 and/or between separate portions of workspace 70. Thecomponents and operation of an example embodiment of a mobile drive unit20 are discussed further below with respect to FIGS. 4 and 5.

Additionally, mobile drive units 20 may be capable of communicating withmanagement module 15 to receive information identifying selectedinventory holders 30, transmit the locations of mobile drive units 20,or exchange any other suitable information to be used by managementmodule 15 or mobile drive units 20 during operation. Mobile drive units20 may communicate with management module 15 wirelessly, using wiredconnections between mobile drive units 20 and management module 15,and/or in any other appropriate manner. As one example, particularembodiments of mobile drive unit 20 may communicate with managementmodule 15 and/or with one another using 802.11, Bluetooth, or InfraredData Association (IrDA) standards, or any other appropriate wirelesscommunication protocol. As another example, in a tracked inventorysystem 10, tracks or other guidance elements upon which mobile driveunits 20 move may be wired to facilitate communication between mobiledrive units 20 and other components of inventory system 10. Furthermore,as noted above, management module 15 may include components ofindividual mobile drive units 20. Thus, for the purposes of thisdescription and the claims that follow, communication between managementmodule 15 and a particular mobile drive unit 20 may representcommunication between components of a particular mobile drive unit 20.In general, mobile drive units 20 may be powered, propelled, andcontrolled in any manner appropriate based on the configuration andcharacteristics of inventory system 10.

Inventory holders 30 store inventory items. In a particular embodiment,inventory holders 30 include multiple storage bins with each storage bincapable of holding one or more types of inventory items. Inventoryholders 30 are capable of being carried, rolled, and/or otherwise movedby mobile drive units 20. In particular embodiments, inventory holder 30may provide additional propulsion to supplement that provided by mobiledrive unit 20 when moving inventory holder 30.

Additionally, in particular embodiments, inventory items 40 may alsohang from hooks or bars (not shown) within or on inventory holder 30. Ingeneral, inventory holder 30 may store inventory items 40 in anyappropriate manner within inventory holder 30 and/or on the externalsurface of inventory holder 30.

Additionally, each inventory holder 30 may include a plurality of faces,and each bin may be accessible through one or more faces of theinventory holder 30. For example, in a particular embodiment, inventoryholder 30 includes four faces. In such an embodiment, bins located at acorner of two faces may be accessible through either of those two faces,while each of the other bins is accessible through an opening in one ofthe four faces. Mobile drive unit 20 may be configured to rotateinventory holder 30 at appropriate times to present a particular faceand the bins associated with that face to an operator or othercomponents of inventory system 10.

Inventory items represent any objects suitable for storage, retrieval,and/or processing in an automated inventory system 10. For the purposesof this description, “inventory items” may represent any one or moreobjects of a particular type that are stored in inventory system 10.Thus, a particular inventory holder 30 is currently “storing” aparticular inventory item if the inventory holder 30 currently holds oneor more units of that type. As one example, inventory system 10 mayrepresent a mail order warehouse facility, and inventory items mayrepresent merchandise stored in the warehouse facility. Duringoperation, mobile drive units 20 may retrieve inventory holders 30containing one or more inventory items requested in an order to bepacked for delivery to a customer or inventory holders 30 carryingpallets containing aggregated collections of inventory items forshipment. Moreover, in particular embodiments of inventory system 10,boxes containing completed orders may themselves represent inventoryitems.

In particular embodiments, inventory system 10 may also include one ormore inventory stations 50. Inventory stations 50 represent locationsdesignated for the completion of particular tasks involving inventoryitems. Such tasks may include the removal of inventory items frominventory holders 30, the introduction of inventory items into inventoryholders 30, the counting of inventory items in inventory holders 30, thedecomposition of inventory items (e.g. from pallet- or case-sized groupsto individual inventory items), the consolidation of inventory itemsbetween inventory holders 30, and/or the processing or handling ofinventory items in any other suitable manner. In particular embodiments,inventory stations 50 may just represent the physical locations where aparticular task involving inventory items can be completed withinworkspace 70. In alternative embodiments, inventory stations 50 mayrepresent both the physical location and also any appropriate equipmentfor processing or handling inventory items, such as scanners formonitoring the flow of inventory items in and out of inventory system10, communication interfaces for communicating with management module15, and/or any other suitable components. Inventory stations 50 may becontrolled, entirely or in part, by human operators or may be fullyautomated. Moreover, the human or automated operators of inventorystations 50 may be capable of performing certain tasks to inventoryitems, such as packing, counting, or transferring inventory items, aspart of the operation of inventory system 10.

Workspace 70 represents an area associated with inventory system 10 inwhich mobile drive units 20 can move and/or inventory holders 30 can bestored. For example, workspace 70 may represent all or part of the floorof a mail-order warehouse in which inventory system 10 operates.Although FIG. 2 shows, for the purposes of illustration, an embodimentof inventory system 10 in which workspace 70 includes a fixed,predetermined, and finite physical space, particular embodiments ofinventory system 10 may include mobile drive units 20 and inventoryholders 30 that are configured to operate within a workspace 70 that isof variable dimensions and/or an arbitrary geometry. While FIG. 2illustrates a particular embodiment of inventory system 10 in whichworkspace 70 is entirely enclosed in a building, alternative embodimentsmay utilize workspaces 70 in which some or all of the workspace 70 islocated outdoors, within a vehicle (such as a cargo ship), or otherwiseunconstrained by any fixed structure.

In operation, management module 15 selects appropriate components tocomplete particular tasks and transmits task assignments 18 to theselected components to trigger completion of the relevant tasks. Eachtask assignment 18 defines one or more tasks to be completed by aparticular component. These tasks may relate to the retrieval, storage,replenishment, and counting of inventory items and/or the management ofmobile drive units 20, inventory holders 30, inventory stations 50 andother components of inventory system 10. Depending on the component andthe task to be completed, a particular task assignment 18 may identifylocations, components, and/or actions associated with the correspondingtask and/or any other appropriate information to be used by the relevantcomponent in completing the assigned task.

In particular embodiments, management module 15 generates taskassignments 18 based, in part, on inventory requests that managementmodule 15 receives from other components of inventory system 10 and/orfrom external components in communication with management module 15.These inventory requests identify particular operations to be completedinvolving inventory items stored or to be stored within inventory system10 and may represent communication of any suitable form. For example, inparticular embodiments, an inventory request may represent a shippingorder specifying particular inventory items that have been purchased bya customer and that are to be retrieved from inventory system 10 forshipment to the customer. Management module 15 may also generate taskassignments 18 independently of such inventory requests, as part of theoverall management and maintenance of inventory system 10. For example,management module 15 may generate task assignments 18 in response to theoccurrence of a particular event (e.g., in response to a mobile driveunit 20 requesting a space to park), according to a predeterminedschedule (e.g., as part of a daily start-up routine), or at anyappropriate time based on the configuration and characteristics ofinventory system 10. After generating one or more task assignments 18,management module 15 transmits the generated task assignments 18 toappropriate components for completion of the corresponding task. Therelevant components then execute their assigned tasks.

With respect to mobile drive units 20 specifically, management module 15may, in particular embodiments, communicate task assignments 18 toselected mobile drive units 20 that identify one or more destinationsfor the selected mobile drive units 20. Management module 15 may selecta mobile drive unit 20 to assign the relevant task based on the locationor state of the selected mobile drive unit 20, an indication that theselected mobile drive unit 20 has completed a previously-assigned task,a predetermined schedule, and/or any other suitable consideration. Thesedestinations may be associated with an inventory request the managementmodule 15 is executing or a management objective the management module15 is attempting to fulfill. For example, the task assignment may definethe location of an inventory holder 30 to be retrieved, an inventorystation 50 to be visited, a storage location where the mobile drive unit20 should park until receiving another task, or a location associatedwith any other task appropriate based on the configuration,characteristics, and/or state of inventory system 10, as a whole, orindividual components of inventory system 10. For example, in particularembodiments, such decisions may be based on the popularity of particularinventory items, the staffing of a particular inventory station 50, thetasks currently assigned to a particular mobile drive unit 20, and/orany other appropriate considerations.

As part of completing these tasks mobile drive units 20 may dock withand transport inventory holders 30 within workspace 70. Mobile driveunits 20 may dock with inventory holders 30 by connecting to, lifting,and/or otherwise interacting with inventory holders 30 in any othersuitable manner so that, when docked, mobile drive units 20 are coupledto and/or support inventory holders 30 and can move inventory holders 30within workspace 70. While the description below focuses on particularembodiments of mobile drive unit 20 and inventory holder 30 that areconfigured to dock in a particular manner, alternative embodiments ofmobile drive unit 20 and inventory holder 30 may be configured to dockin any manner suitable to allow mobile drive unit 20 to move inventoryholder 30 within workspace 70. Additionally, as noted below, inparticular embodiments, mobile drive units 20 represent all or portionsof inventory holders 30. In such embodiments, mobile drive units 20 maynot dock with inventory holders 30 before transporting inventory holders30 and/or mobile drive units 20 may each remain continually docked witha particular inventory holder 30.

While the appropriate components of inventory system 10 completeassigned tasks, management module 15 may interact with the relevantcomponents to ensure the efficient use of space, equipment, manpower,and other resources available to inventory system 10. As one specificexample of such interaction, management module 15 is responsible, inparticular embodiments, for planning the paths mobile drive units 20take when moving within workspace 70 and for allocating use of aparticular portion of workspace 70 to a particular mobile drive unit 20for purposes of completing an assigned task. In such embodiments, mobiledrive units 20 may, in response to being assigned a task, request a pathto a particular destination associated with the task. Moreover, whilethe description below focuses on one or more embodiments in which mobiledrive unit 20 requests paths from management module 15, mobile driveunit 20 may, in alternative embodiments, generate its own paths.

Components of inventory system 10 may provide information to managementmodule 15 regarding their current state, other components of inventorysystem 10 with which they are interacting, and/or other conditionsrelevant to the operation of inventory system 10. This may allowmanagement module 15 to utilize feedback from the relevant components toupdate algorithm parameters, adjust policies, or otherwise modify itsdecision-making to respond to changes in operating conditions or theoccurrence of particular events.

In addition, while management module 15 may be configured to managevarious aspects of the operation of the components of inventory system10, in particular embodiments, the components themselves may also beresponsible for decision-making relating to certain aspects of theiroperation, thereby reducing the processing load on management module 15.

Thus, based on its knowledge of the location, current state, and/orother characteristics of the various components of inventory system 10and an awareness of all the tasks currently being completed, managementmodule 15 can generate tasks, allot usage of system resources, andotherwise direct the completion of tasks by the individual components ina manner that optimizes operation from a system-wide perspective.Moreover, by relying on a combination of both centralized, system-widemanagement and localized, component-specific decision-making, particularembodiments of inventory system 10 may be able to support a number oftechniques for efficiently executing various aspects of the operation ofinventory system 10. As a result, particular embodiments of managementmodule 15 may, by implementing one or more management techniquesdescribed below, enhance the efficiency of inventory system 10 and/orprovide other operational benefits.

FIG. 3 illustrates in greater detail the components of a particularembodiment of management module 15. As shown, the example embodimentincludes a resource scheduling module 92, a route planning module 94, asegment reservation module 96, an inventory module 97, a communicationinterface module 98, a processor 90, and a memory 91. Management module15 may represent a single component, multiple components located at acentral location within inventory system 10, or multiple componentsdistributed throughout inventory system 10. For example, managementmodule 15 may represent components of one or more mobile drive units 20that are capable of communicating information between the mobile driveunits 20 and coordinating the movement of mobile drive units 20 withinworkspace 70. In general, management module 15 may include anyappropriate combination of hardware and/or software suitable to providethe described functionality.

Processor 90 is operable to execute instructions associated with thefunctionality provided by management module 15. Processor 90 maycomprise one or more general purpose computers, dedicatedmicroprocessors, or other processing devices capable of communicatingelectronic information. Examples of processor 90 include one or moreapplication-specific integrated circuits (ASICs), field programmablegate arrays (FPGAs), digital signal processors (DSPs) and any othersuitable specific or general purpose processors.

Memory 91 stores processor instructions, inventory requests, reservationinformation, state information for the various components of inventorysystem 10 and/or any other appropriate values, parameters, orinformation utilized by management module 15 during operation. Memory 91may represent any collection and arrangement of volatile or nonvolatile,local or remote devices suitable for storing data. Examples of memory 91include, but are not limited to, random access memory (RAM) devices,read only memory (ROM) devices, magnetic storage devices, opticalstorage devices or any other suitable data storage devices.

Resource scheduling module 92 processes received inventory requests andgenerates one or more assigned tasks to be completed by the componentsof inventory system 10. Resource scheduling module 92 may also selectone or more appropriate components for completing the assigned tasksand, using communication interface module 98, communicate the assignedtasks to the relevant components. Additionally, resource schedulingmodule 92 may also be responsible for generating assigned tasksassociated with various management operations, such as prompting mobiledrive units 20 to recharge batteries or have batteries replaced,instructing inactive mobile drive units 20 to park in a location outsidethe anticipated traffic flow or a location near the anticipated site offuture tasks, and/or directing mobile drive units 20 selected for repairor maintenance to move towards a designated maintenance station.

Route planning module 94 receives route requests from mobile drive units20. These route requests identify one or more destinations associatedwith a task the requesting mobile drive unit 20 is executing. Inresponse to receiving a route request, route planning module 94generates a path to one or more destinations identified in the routerequest. Route planning module 94 may implement any appropriatealgorithms utilizing any appropriate parameters, factors, and/orconsiderations to determine the appropriate path. After generating anappropriate path, route planning module 94 transmits a route responseidentifying the generated path to the requesting mobile drive unit 20using communication interface module 98.

Segment reservation module 96 receives reservation requests from mobiledrive units 20 attempting to move along paths generated by routeplanning module 94. These reservation requests request the use of aparticular portion of workspace 70 (referred to herein as a “segment”)to allow the requesting mobile drive unit 20 to avoid collisions withother mobile drive units 20 while moving across the reserved segment. Inresponse to received reservation requests, segment reservation module 96transmits a reservation response granting or denying the reservationrequest to the requesting mobile drive unit 20 using the communicationinterface module 98.

The inventory module 97 maintains information about the location andnumber of inventory items 40 in the inventory system 10. Information canbe maintained about the number of inventory items 40 in a particularinventory holder 30, and the maintained information can include thelocation of those inventory items 40 in the inventory holder 30. Theinventory module 97 can also communicate with the mobile drive units 20,utilizing task assignments 18 to maintain, replenish or move inventoryitems 40 within the inventory system 10.

Communication interface module 98 facilitates communication betweenmanagement module 15 and other components of inventory system 10,including reservation responses, reservation requests, route requests,route responses, and task assignments. These reservation responses,reservation requests, route requests, route responses, and taskassignments may represent communication of any form appropriate based onthe capabilities of management module 15 and may include any suitableinformation. Depending on the configuration of management module 15,communication interface module 98 may be responsible for facilitatingeither or both of wired and wireless communication between managementmodule 15 and the various components of inventory system 10. Inparticular embodiments, management module 15 may communicate usingcommunication protocols such as 802.11, Bluetooth, or Infrared DataAssociation (IrDA) standards. Furthermore, management module 15 may, inparticular embodiments, represent a portion of mobile drive unit 20 orother components of inventory system 10. In such embodiments,communication interface module 98 may facilitate communication betweenmanagement module 15 and other parts of the same system component.

In general, resource scheduling module 92, route planning module 94,segment reservation module 96, inventory module 97, and communicationinterface module 98 may each represent any appropriate hardware and/orsoftware suitable to provide the described functionality. In addition,as noted above, management module 15 may, in particular embodiments,represent multiple different discrete components and any or all ofresource scheduling module 92, route planning module 94, segmentreservation module 96, inventory module 97, and communication interfacemodule 98 may represent components physically separate from theremaining elements of management module 15. Moreover, any two or more ofresource scheduling module 92, route planning module 94, segmentreservation module 96, inventory module 97, and communication interfacemodule 98 may share common components. For example, in particularembodiments, resource scheduling module 92, route planning module 94,segment reservation module 96, and inventory module 97 representcomputer processes executing on processor 90 and communication interfacemodule 98 comprises a wireless transmitter, a wireless receiver, and arelated computer process executing on processor 90.

FIGS. 4 and 5 illustrate in greater detail the components of aparticular embodiment of mobile drive unit 20. In particular, FIGS. 4and 5 include a front and side view of an example mobile drive unit 20.Mobile drive unit 20 includes a docking head 110, a drive module 120, adocking actuator 130, and a control module 170. Additionally, mobiledrive unit 20 may include one or more sensors configured to detect ordetermine the location of mobile drive unit 20, inventory holder 30,and/or other appropriate elements of inventory system 10. In theillustrated embodiment, mobile drive unit 20 includes a position sensor140, a holder sensor 150, an obstacle sensor 160, and an identificationsignal transmitter 162.

Docking head 110, in particular embodiments of mobile drive unit 20,couples mobile drive unit 20 to inventory holder 30 and/or supportsinventory holder 30 when mobile drive unit 20 is docked to inventoryholder 30. Docking head 110 may additionally allow mobile drive unit 20to maneuver inventory holder 30, such as by lifting inventory holder 30,propelling inventory holder 30, rotating inventory holder 30, and/ormoving inventory holder 30 in any other appropriate manner. Docking head110 may also include any appropriate combination of components, such asribs, spikes, and/or corrugations, to facilitate such manipulation ofinventory holder 30. For example, in particular embodiments, dockinghead 110 may include a high-friction portion that abuts a portion ofinventory holder 30 while mobile drive unit 20 is docked to inventoryholder 30. In such embodiments, frictional forces created between thehigh-friction portion of docking head 110 and a surface of inventoryholder 30 may induce translational and rotational movement in inventoryholder 30 when docking head 110 moves and rotates, respectively. As aresult, mobile drive unit 20 may be able to manipulate inventory holder30 by moving or rotating docking head 110, either independently or as apart of the movement of mobile drive unit 20 as a whole.

Drive module 120 propels mobile drive unit 20 and, when mobile driveunit 20 and inventory holder 30 are docked, inventory holder 30. Drivemodule 120 may represent any appropriate collection of componentsoperable to propel mobile drive unit 20. For example, in the illustratedembodiment, drive module 120 includes motorized axle 122, a pair ofmotorized wheels 124, and a pair of stabilizing wheels 126. Onemotorized wheel 124 is located at each end of motorized axle 122, andone stabilizing wheel 126 is positioned at each end of mobile drive unit20.

Docking actuator 130 moves docking head 110 towards inventory holder 30to facilitate docking of mobile drive unit 20 and inventory holder 30.Docking actuator 130 may also be capable of adjusting the position ororientation of docking head 110 in other suitable manners to facilitatedocking. Docking actuator 130 may include any appropriate components,based on the configuration of mobile drive unit 20 and inventory holder30, for moving docking head 110 or otherwise adjusting the position ororientation of docking head 110. For example, in the illustratedembodiment, docking actuator 130 includes a motorized shaft (not shown)attached to the center of docking head 110. The motorized shaft isoperable to lift docking head 110 as appropriate for docking withinventory holder 30.

Drive module 120 may be configured to propel mobile drive unit 20 in anyappropriate manner. For example, in the illustrated embodiment,motorized wheels 124 are operable to rotate in a first direction topropel mobile drive unit 20 in a forward direction. Motorized wheels 124are also operable to rotate in a second direction to propel mobile driveunit 20 in a backward direction. In the illustrated embodiment, drivemodule 120 is also configured to rotate mobile drive unit 20 by rotatingmotorized wheels 124 in different directions from one another or byrotating motorized wheels 124 at different speeds from one another.

Position sensor 140 represents one or more sensors, detectors, or othercomponents suitable for determining the location of mobile drive unit 20in any appropriate manner. For example, in particular embodiments, theworkspace 70 associated with inventory system 10 includes a number offiducial marks that mark points on a two-dimensional grid that coversall or a portion of workspace 70. In such embodiments, position sensor140 may include a camera and suitable image- and/or video-processingcomponents, such as an appropriately-programmed digital signalprocessor, to allow position sensor 140 to detect fiducial marks withinthe camera's field of view. Control module 170 may store locationinformation that position sensor 140 updates as position sensor 140detects fiducial marks. As a result, position sensor 140 may utilizefiducial marks to maintain an accurate indication of the location mobiledrive unit 20 and to aid in navigation when moving within workspace 70.

Holder sensor 150 represents one or more sensors, detectors, or othercomponents suitable for detecting inventory holder 30 and/ordetermining, in any appropriate manner, the location of inventory holder30, as an absolute location or as a position relative to mobile driveunit 20. Holder sensor 150 may be capable of detecting the location of aparticular portion of inventory holder 30 or inventory holder 30 as awhole. Mobile drive unit 20 may then use the detected information fordocking with or otherwise interacting with inventory holder 30.

Obstacle sensor 160 represents one or more sensors capable of detectingobjects located in one or more different directions in which mobiledrive unit 20 is capable of moving. Obstacle sensor 160 may utilize anyappropriate components and techniques, including optical, radar, sonar,pressure-sensing and/or other types of detection devices appropriate todetect objects located in the direction of travel of mobile drive unit20. In particular embodiments, obstacle sensor 160 may transmitinformation describing objects it detects to control module 170 to beused by control module 170 to identify obstacles and to take appropriateremedial actions to prevent mobile drive unit 20 from colliding withobstacles and/or other objects.

Obstacle sensor 160 may also detect signals transmitted by other mobiledrive units 20 operating in the vicinity of the illustrated mobile driveunit 20. For example, in particular embodiments of inventory system 10,one or more mobile drive units 20 may include an identification signaltransmitter 162 that transmits a drive identification signal. The driveidentification signal indicates to other mobile drive units 20 that theobject transmitting the drive identification signal is in fact a mobiledrive unit. Identification signal transmitter 162 may be capable oftransmitting infrared, ultraviolet, audio, visible light, radio, and/orother suitable signals that indicate to recipients that the transmittingdevice is a mobile drive unit 20.

Additionally, in particular embodiments, obstacle sensor 160 may also becapable of detecting state information transmitted by other mobile driveunits 20. For example, in particular embodiments, identification signaltransmitter 162 may be capable of including state information relatingto mobile drive unit 20 in the transmitted identification signal. Thisstate information may include, but is not limited to, the position,velocity, direction, and the braking capabilities of the transmittingmobile drive unit 20. In particular embodiments, mobile drive unit 20may use the state information transmitted by other mobile drive units toavoid collisions when operating in close proximity with those othermobile drive units.

Control module 170 monitors and/or controls operation of drive module120 and docking actuator 130. Control module 170 may also receiveinformation from sensors such as position sensor 140 and holder sensor150 and adjust the operation of drive module 120, docking actuator 130,and/or other components of mobile drive unit 20 based on thisinformation. Additionally, in particular embodiments, mobile drive unit20 may be configured to communicate with a management device ofinventory system 10 and control module 170 may receive commandstransmitted to mobile drive unit 20 and communicate information back tothe management device utilizing appropriate communication components ofmobile drive unit 20. Control module 170 may include any appropriatehardware and/or software suitable to provide the describedfunctionality. In particular embodiments, control module 170 includes ageneral-purpose microprocessor programmed to provide the describedfunctionality. Additionally, control module 170 may include all orportions of docking actuator 130, drive module 120, position sensor 140,and/or holder sensor 150, and/or share components with any of theseelements of mobile drive unit 20.

Moreover, in particular embodiments, control module 170 may includehardware and software located in components that are physically distinctfrom the device that houses drive module 120, docking actuator 130,and/or the other components of mobile drive unit 20 described above. Forexample, in particular embodiments, each mobile drive unit 20 operatingin inventory system 10 may be associated with a software process(referred to here as a “drive agent”) operating on a server that is incommunication with the device that houses drive module 120, dockingactuator 130, and other appropriate components of mobile drive unit 20.This drive agent may be responsible for requesting and receiving tasks,requesting and receiving routes, transmitting state informationassociated with mobile drive unit 20, and/or otherwise interacting withmanagement module 15 and other components of inventory system 10 onbehalf of the device that physically houses drive module 120, dockingactuator 130, and the other appropriate components of mobile drive unit20. As a result, for the purposes of this description and the claimsthat follow, the term “mobile drive unit” includes software and/orhardware, such as agent processes, that provides the describedfunctionality on behalf of mobile drive unit 20 but that may be locatedin physically distinct devices from the drive module 120, dockingactuator 130, and/or the other components of mobile drive unit 20described above.

While FIGS. 4 and 5 illustrate a particular embodiment of mobile driveunit 20 containing certain components and configured to operate in aparticular manner, mobile drive unit 20 may represent any appropriatecomponent and/or collection of components configured to transport and/orfacilitate the transport of inventory holders 30. As another example,mobile drive unit 20 may represent part of an overhead crane system inwhich one or more crane assemblies are capable of moving within anetwork of wires or rails to a position suitable to dock with aparticular inventory holder 30. After docking with inventory holder 30,the crane assembly may then lift inventory holder 30 and move inventoryto another location for purposes of completing an assigned task.

Furthermore, in particular embodiments, mobile drive unit 20 mayrepresent all or a portion of inventory holder 30. Inventory holder 30may include motorized wheels or any other components suitable to allowinventory holder 30 to self-propel. As one specific example, a portionof inventory holder 30 may be responsive to magnetic fields. Inventorysystem 10 may be able to generate one or more controlled magnetic fieldscapable of propelling, maneuvering and/or otherwise controlling theposition of inventory holder 30 as a result of the responsive portion ofinventory holder 30. In such embodiments, mobile drive unit 20 mayrepresent the responsive portion of inventory holder 30 and/or thecomponents of inventory system 10 responsible for generating andcontrolling these magnetic fields. While this description providesseveral specific examples, mobile drive unit 20 may, in general,represent any appropriate component and/or collection of componentsconfigured to transport and/or facilitate the transport of inventoryholders 30.

FIG. 6 illustrates in greater detail the components of a particularembodiment of inventory holder 30. In particular, FIG. 6 illustrates thestructure and contents of one side of an example inventory holder 30. Ina particular embodiment, inventory holder 30 may comprise any number offaces with similar or different structure. As illustrated, inventoryholder 30 includes a frame 310, a plurality of legs 328, and a dockingsurface 350.

Frame 310 holds inventory items 40. Frame 310 provides storage space forstoring inventory items 40 external or internal to frame 310. Thestorage space provided by frame 310 may be divided into a plurality ofinventory bins 320, each capable of holding inventory items 40.Inventory bins 320 may include any appropriate storage elements, such asbins, compartments, or hooks.

In a particular embodiment, frame 310 is composed of a plurality oftrays 322 stacked upon one another and attached to or stacked on a base318. In such an embodiment, inventory bins 320 may be formed by aplurality of adjustable dividers 324 that may be moved to resize one ormore inventory bins 320. In alternative embodiments, frame 310 mayrepresent a single inventory bin 320 that includes a single tray 322 andno adjustable dividers 324. Additionally, in particular embodiments,frame 310 may represent a load-bearing surface mounted on mobilityelement 330. Inventory items 40 may be stored on such an inventoryholder 30 by being placed on frame 310. In general, frame 310 mayinclude internal and/or external storage space divided into anyappropriate number of inventory bins 320 in any appropriate manner.

Additionally, in a particular embodiment, frame 310 may include aplurality of device openings 326 that allow mobile drive unit 20 toposition docking head 110 adjacent docking surface 350. The size, shape,and placement of device openings 326 may be determined based on thesize, the shape, and other characteristics of the particular embodimentof mobile drive unit 20 and/or inventory holder 30 utilized by inventorysystem 10. For example, in the illustrated embodiment, frame 310includes four legs 328 that form device openings 326 and allow mobiledrive unit 20 to position mobile drive unit 20 under frame 310 andadjacent to docking surface 350. The length of legs 328 may bedetermined based on a height of mobile drive unit 20.

Docking surface 350 comprises a portion of inventory holder 30 thatcouples to, abuts, and/or rests upon a portion of docking head 110, whenmobile drive unit 20 is docked to inventory holder 30. Additionally,docking surface 350 supports a portion or all of the weight of inventoryholder 30 while inventory holder 30 is docked with mobile drive unit 20.The composition, shape, and/or texture of docking surface 350 may bedesigned to facilitate maneuvering of inventory holder 30 by mobiledrive unit 20. For example, as noted above, in particular embodiments,docking surface 350 may comprise a high-friction portion. When mobiledrive unit 20 and inventory holder 30 are docked, frictional forcesinduced between docking head 110 and this high-friction portion mayallow mobile drive unit 20 to maneuver inventory holder 30.Additionally, in particular embodiments, docking surface 350 may includeappropriate components suitable to receive a portion of docking head110, couple inventory holder 30 to mobile drive unit 20, and/orfacilitate control of inventory holder 30 by mobile drive unit 20.

Holder identifier 360 marks a predetermined portion of inventory holder30 and mobile drive unit 20 may use holder identifier 360 to align withinventory holder 30 during docking and/or to determine the location ofinventory holder 30. More specifically, in particular embodiments,mobile drive unit 20 may be equipped with components, such as holdersensor 150, that can detect holder identifier 360 and determine itslocation relative to mobile drive unit 20. As a result, mobile driveunit 20 may be able to determine the location of inventory holder 30 asa whole. For example, in particular embodiments, holder identifier 360may represent a reflective marker that is positioned at a predeterminedlocation on inventory holder 30 and that holder sensor 150 can opticallydetect using an appropriately-configured camera.

Depending on the configuration and characteristics of mobile drive unit20 and inventory system 10, mobile drive unit 20 may move inventoryholder 30 using a variety of appropriate methods. In a particularembodiment, mobile drive unit 20 is capable of moving inventory holder30 along a two-dimensional grid, combining movement along straight-linesegments with ninety-degree rotations and arcing paths to transportinventory holder 30 from the first location to the second location.Additionally, while moving, mobile drive unit 20 may use fixed objectslocated in the workspace as reference points to assist in navigation.For example, in particular embodiments, inventory system 10 includesmultiple fiducial marks. Mobile drive unit 20 may be configured todetect fiducial marks and to determine the location of mobile drive unit20 and/or measure its movement based on the detection of fiducial marks.

After mobile drive unit 20 arrives at the second location, mobile driveunit 20 may perform appropriate operations to facilitate access toinventory items 40 stored in inventory holder 30. For example, mobiledrive unit 20 may rotate inventory holder 30 to present a particularface of inventory holder 30 to an operator of inventory system 10 orother suitable party, such as a packer selecting inventory items 40 frominventory holder 30. Mobile drive unit 20 may also undock from inventoryholder 30. Alternatively, instead of undocking at the second location,mobile drive unit 20 may transport inventory holder 30 back to the firstlocation or to a third location after any appropriate actions have beentaken involving inventory items 40. For example, after a packer hasremoved particular inventory items 40 from inventory holder 30, mobiledrive unit 20 may return inventory holder 30 to its original storagelocation, a new storage location, or another inventory station. Mobiledrive unit 20 may then undock from inventory holder 30 at this newlocation.

As described above, embodiments herein are directed to systems formoving resources and/or inventory within an inventory system usingmobile drive units. In particular, apparatuses, systems, and methodsdiscussed herein are directed to moving resources and/or inventorywithin the inventory system by employing vertically mobile drive unitscapable of ascending or descending vertical elements within an inventorymanagement facility, as described above with reference to the system 100shown in FIG. 1. Mobile drive units and inventory may be used inconjunction with systems such as system 100 for transferring inventoryor other resources to and from vertically mobile drive units. Inaddition, vertically mobile drive units and systems for controllingvertically mobile drive units may possess any features or combination offeatures as disclosed above with reference to mobile drive units andsystems shown in FIGS. 2-5. In some cases, vertically mobile drive unitsmay be operable to transport inventory holders such as the inventoryholder 30 as described with reference to FIG. 6. According to someembodiments, this capability may extend to vertically transportinginventory holders.

FIG. 7 show a vertically mobile drive unit 700 with a vertical elementgrasping mechanism 720 for implementing aspects of an inventory system,such as system 100 shown in FIG. 1, in accordance with embodiments. FIG.7 illustrates the example drive unit 700 in a top-down view, showingwith particularity aspects of a vertical element grasping mechanism 720.The drive unit 700 includes a body 706 which has several features incommon with mobile drive units as discussed above with reference toFIGS. 2-5. The drive unit 700 includes a horizontal drive mechanismincluding, e.g., drive wheels 702 and stabilizing wheels 704 positionedto support the drive unit and provide for horizontal displacement on theground. The drive unit 700 also includes resource retention elements,such as a resource platform 712, which can further include features foronloading or offloading a resource. As shown, the resource platform 712defines a conveyor; however it will be understood that the resourceplatform 712 can be replaced with a robotic platform, robotic arm, orthe like, without deviating from the spirit of this disclosure. The body706 also contains a control element 716 which can contain onboardprocessing, memory, and networking modules for enabling the operation ofthe drive unit 700 and the integration of the drive unit into aninventory system. Also shown is are sensors 708 configured to detect ordetermine the location of the drive unit 700 and/or other appropriateelements of an inventory system.

According to some embodiments, the vertically mobile drive unit caninclude retention elements in addition to or in place of the resourceplatform 712. For example, in some embodiments, the drive unit 700 caninclude any suitable features of the mobile drive units 20.Specifically, embodiments include vertically mobile drive units havingfeatures for docking with inventory holders 30 (see FIGS. 2-5), e.g.docking mechanisms such as docking head 110 and docking actuator 130shown in FIGS. 4-5 for interfacing with inventory holders like inventoryholder 30 as shown in FIGS. 2 and 6. Vertically mobile drive units canalso include further sensors for detecting a payload, similar to holdersensors 150 for detecting inventory holder 30 or other payload. In somecases, vertically mobile drive units can include retaining featureshaving multiple functionalities, including capabilities of transportinglightweight materials such as totes, boxes, or other resources, andheavier cargo such as inventory holders.

The vertical element grasping mechanism 720 is connected with the driveunit 700 at a grasping end 714. The grasping mechanism 720 includes adrive mechanism including at least one drive element 736 with at leastone driving contact element 738. Two grasping arms 726 a,b extend from apivoting connection 722 so as to surround a vertical element 740 andbring the driving contact element 738 into contact with the verticalelement. Gripping elements 728 a,b also containing contact elements 732a,b, are connected with the grasping arms 726 a,b, so that they comeinto contact with the vertical element 740. The grasping arms 726 a,bcan be locked together when fully surrounding the vertical element 740by, e.g., locking features 730 a,b. Suitable locking features canoperate by way of forming a mechanical connection, by hydraulic force,by magnetic force, or any other suitable locking means. The graspingarms 726 a,b can open and close by predetermined ranges of motion 734a,b which are at least sufficient to allow the grasping mechanism 720 toencompass and grasp a vertical element in an inventory system.

The grasping mechanism 720 is connected with the body 706 of the driveunit 700. In accordance with some embodiments, the grasping mechanism720 is positioned at an end of a mechanical arm 722 which can connectwith the body 706 of the drive unit 700 at a pivoting actuator 710. Insome embodiments, the mechanical arm 722 can rest inside a cavity 718 ofthe drive unit 700 during ordinary operation, while capable of swingingoutward to maneuver the drive unit when the drive unit is suspended bythe grasping mechanism. By resting within the cavity, 718, themechanical arm 722 can reduce the overall moment exerted by the driveunit 700 on the vertical element 740 when the drive unit is suspendedalong the vertical element.

FIG. 8 shows the vertically mobile drive unit 700 in a side view. Asshown, the drive unit 700 is capable to mechanically grasping a verticalelement 740 (shown here as a vertical pole) with grasping arms 726 a,bof the grasping mechanism 720. The gripping elements 728 a,b havesufficient height to employ at least two vertically separated contactelements 738. The contact elements 738 can be rollers, sliders, gearedrollers, rollers with an adhesive, tacky, or gripping surface, or othercomparable material or structure for firmly securing the verticalelement 740 by the grasping mechanism 720, and for supporting the weightof the drive unit 700, along with any resource or cargo on the driveunit, while the drive unit is ascending or descending the verticalelement. Also shown, the sensors 708 can include multiple sensorsdisposed at different positions around the drive unit 700, e.g., at thegrasping end 714 where the sensors may be operable to locate a verticalelement to enable grasping; underneath the drive unit where the sensorsmay be operable to locate markings or other navigation aids along afloor of an inventory system; or at various other positions for sensingan environment around the drive unit.

According to some embodiments, sensors 708 can detect a verticalposition of the drive unit 700, e.g. by sensing the proximity of a floorof an inventory facility (e.g., visual, radar, laser, altitude sensors,or comparable sensors can be used to determine a position of proximateobjects such as the ground floor beneath the drive unit, or a mezzaninelevel of a facility adjacent to, above, or below the drive unit).Visual, radar, laser, or comparable sensors can also be configured todetect location indicia positioned in the environment, such as markings,machine-readable codes, or colors placed in an inventory facility todenote locations, heights, and relative positions of features such asthe levels in the inventory facility. Such markings may or may not be inhuman-visible spectra. In some embodiments, sensors 708 can includeelectronics configured to detect a proximity signal, e.g. by RFID orcomparable sensors, to interact with location beacons or similartransmitters positioned throughout parts of an inventory facility, suchas embedded in the ground and/or mezzanine levels of a multi-levelinventory facility, or positioned in or on the vertical elements. Insome embodiments, sensors 708 include sensors in the grasping end 714 orgrasping mechanism 720 for detecting the distance of travel of the driveunit 700, e.g. by tracking and storing information on vertical travelleddistance.

FIG. 9 shows the vertically mobile drive unit 700 in a top view with themechanical arm 722 extended, such that the body 706 of the mobile driveunit is both rotated with respect to its initial position, and aroundthe vertical element 740. The drive unit 700 is shown rotated about anarc 742 which, in some cases, may be about 90 degrees. In various otherembodiments, the mechanical arm may provide for rotating the drive unit700 around any suitable path, which may vary from 0 to about 180degrees, from 45 to 135 degrees, or from 60 to about 120 degrees. Inthis extended configuration, the body 706 of the drive unit 700 is alsogenerally farther from the vertical element 740 than in the closeconfiguration show in FIGS. 7-8. Thus, both the rotation of the driveunit 700, and the extension of the drive unit away from the verticalelement 740, can be employed to position the drive unit 700 above afloor, level, or platform of an inventory management facility in aninventory system. In some alternative embodiments, the mechanical arm722 may also extend, so that the drive unit 700 can be further displacedhorizontally relative to the vertical element 740.

It will be understood that the features of the vertically mobile driveunit 700 shown in FIGS. 7-9 may be combined with suitable features ofthe subsequent drive units described below. For example, variousconfigurations of a drive unit body (e.g. body 706) may be combined withany suitable grasping mechanism, mechanical arm, grasping elements, orthe like. Variations of a drive unit employing different combinations ofthe drive unit bodies, mechanical arms, and grasping mechanisms arewithin the scope of this disclosure, except where expressly providedotherwise. A grasping mechanism, such as grasping mechanism 720, maypossess as few as two gripping elements (e.g., gripping elements 728 a,728 b) or may have a greater number of gripping elements. Preferably,drive elements (e.g. drive element 736) and gripping elements (e.g.,gripping elements 728 a,b) will provide for points of contact around avertical element from at least three directions, but in variousalternative embodiments, a grasping mechanism may have additional driveelements and/or gripping elements spaced to grasp the vertical elementfrom more than three directions. Drive and gripping elements arepreferably spaced evenly for interacting with a symmetrical (i.e.,circular, square, or rectangular) vertical element; but may be providedaccording to an element-specific geometry to interact with verticalelements of complex shapes (e.g., I-beams or comparable structuralshapes).

FIG. 10 shows an alternative vertical element grasping mechanism 800which can be combined with a vertically mobile drive unit similar to thedrive unit 700 of FIG. 7 or the drive unit 103 shown in FIG. 1, inaccordance with embodiments. The grasping mechanism 800 is shown in atop-down view. The grasping mechanism 800 includes a rigid U-shapedmember 822 which is connectible with a drive unit by a mechanical arm840. The mechanical arm 840 can be formed of multiple linkages formingan articulating assembly, e.g., first, second, and third linkages 842,844, 846 connected together at pivotal connections 848, 850, to providethe grasping mechanism 800 with multiple degrees of freedom. In variousalternative embodiments, the mechanical arm 840 can employ more, orfewer, linkages. In alternative embodiments, the mechanical arm 840 canalso be arranged to extend from a cavity in a body of a drive unit(e.g., similar to cavity 718 of drive unit 700 shown in FIGS. 7-10), orcan extend from a side of the drive unit body 806.

The rigid U-shaped member 822 of the grasping mechanism 700 employs astationary contact element 820 that extends from the grasping mechanism,and movable contact elements 828 a,b positioned on grasping elements 826a,b. The grasping elements 826 a,b can move inward by, e.g. actuators824 a,b. According to some embodiments, the linear actuators 824 a,b,can be pistons, gear-driven actuators, or any other suitable linearactuator. According to some embodiments, the actuators 824 a,b can locktogether when the grasping mechanism 700 is grasping a vertical element,e.g., using a mechanically interlocking mechanism or other suitableinterlocking mechanism. The grasping elements 826 a,b can be stationarywith respect to the linear actuators 824 a,b or may be pivotallyconnected and able to rotate in order to better align with and contact avertical element.

A grasping mechanism can be connected with a drive unit according to avariety of configurations, and able to move relative to a verticalelement according to a variety of different modes. FIG. 11 is asimplified diagram showing a first mode 1100 of moving the drive unit700 (see FIG. 7) onto an upper level 1102 of an inventory managementfacility, in accordance with embodiments. According to the mode 1100,drive unit 700, which partially encloses its grasping mechanism, canretain the vertical element 1104 using the grasping mechanism 720 whilebeing oriented sidelong to or away from the upper level 1102. The driveunit 700 can then translate by rotating toward the upper level 1102until the drive unit is substantially above the upper level, where itcan proceed to disengage the grasping mechanism 720 from the verticalelement 1104 and move onto the upper level.

FIG. 12 is a simplified diagram showing a second mode 1200 of moving adrive unit 800 (see FIG. 10) with an articulating mechanical arm onto anupper level 1102 of an inventory management facility, in accordance withembodiments. According to the second mode 1200, the drive unit 800 canretain the vertical element 1104 using the grasping mechanism 820 whilethe drive unit is oriented sidelong to or away from the upper level1102. The drive unit 800 can then translate by rotating toward the upperlevel 1102, similar to the mode 1100 described above with reference toFIG. 11. As a point around which the drive unit 800 pivots moves fartherfrom a center of mass of the drive unit, the drive unit can be placedfarther onto the upper level 1102.

FIG. 13 illustrates a third a mode 1300 of moving a drive unit 800 (seeFIG. 10) onto an upper level 1302 of an inventory management facility,in accordance with embodiments. The third mode 1300 illustrates onemechanism by which a drive unit 800 can navigate onto an upper level1302 from an adjacent vertical element 1304 even when the verticalelement and upper level 1302 are positioned very close together.According to this third mode 1300, a drive unit can ascend or descendwhile in a first orientation 1300 a, in which the drive unit 800 isdrawn close to the vertical element 1304 to reduce load on the graspingmechanism 820. Then, the drive unit 800 can be reoriented to a secondorientation 1300 b, which draws the drive unit away from the upper level1302 and allows the drive unit to ascend or descend in the spaceimmediately adjacent to the second level 1302 without causing the driveunit to collide with the second level. A third orientation 1300 c placesthe drive unit 800 above the upper level 1302.

According to some embodiments, a drive unit can rotate around a verticalelement without necessitating the use of a mechanical arm. For example,FIG. 14 shows a simplified perspective view of a grasping mechanism 1400with rotating contact elements 1412, 1406 a in drive element 1410 andgripping element 1404 a, respectively. Drive elements 1410 and grippingelement 1404 a are shown connected with a rigid U-shaped element 1402herein, however, it will be understood that the features describedherein may also apply to grasping mechanism using movable grasping arms.

Rotating contact elements can provide for circular or helical movementaround a vertical element, in accordance with embodiments. In a firstconfiguration 1400 a, or a vertical movement configuration, the contactelements 1412, 1406 a are oriented vertically, so that a drive unitemploying the grasping mechanism 1400 will transit vertically when thegrasping mechanism 1400 is engaged with a vertical element. In a secondconfiguration 1400 b, or a rotational configuration, the contactelements 1412, 1406 a have been rotated according to a predetermined arc1420 via rotating elements 1414, 1408 a, such that the contact elementsno longer point up and down. According to some embodiments, the rotatingelements 1414, 1408 a can rotate 90 degrees such that the resultingconfiguration allows the grasping mechanism 1400 to instead rotate adrive unit in a circular path around a vertical element to which thedrive unit has attached. Alternatively, the rotating elements 1414, 1408a can rotate by less than 90 degrees such that the resultingconfiguration allows the grasping mechanism 1400 to instead promote ahelical path by a drive unit attached with a vertical element, as shownbelow with reference to FIG. 15.

According to some alternative embodiments, multiple sets of contactelements similar to contact elements 1412, 1406 a may be provided, afirst set being oriented vertically as shown in the first configuration1400 a, and a second set being oriented horizontally or at an angle, asshown in the second configuration 1400 b. Rather than causing individualcontact elements to rotate by way of a rotating element such as rotatingelements 1414, 1408 a, the alternative grasping mechanism can alternatebetween utilizing the first set and the second set. For example, totransition from vertical motion to horizontal or helical rotation arounda vertical element, gripping elements in the second configuration 1400 bcan be brought into contact with the vertical element, followed byremoval of the gripping elements in the first configuration 1400 a.

FIG. 15 illustrates a fourth example mode 1500 of moving a drive unit1506 onto an upper level 1502 of an inventory management facility. Inthis mode 1500, the drive unit 1506 is attached with a vertical element1504 by way of a grasping mechanism 1400. In order to ascend to an upperlevel 1502, the drive unit 1506 can ascend beyond the second level to aheight 1508 above the second level. Clearance 1510 is sufficient toallow the drive unit 1506 to clear the upper level 1502 while the driveunit is oriented away from the upper level in a first orientation 1500a. Once the drive unit 1506 is above the upper level 1502, the graspingmechanism 1400 can adjust to a rotational configuration 1400 b in whichthe drive unit moves in a circular or helical path to rotate around thevertical element 1504 and onto the second level 1502.

Various embodiments above describe vertically mobile drive units havinggrasping mechanisms positioned outside a body of the drive unit.However, according to various embodiments, grasping mechanisms may beincluded within a drive unit body as well. For example, FIG. 16 shows avertically mobile drive unit 1600 with an internal vertical elementgrasping mechanism 1620 for implementing aspects of an inventory system,in accordance with embodiments. The drive unit 1600 includes a body 1602similar to the drive unit body 700 shown in FIG. 7, which may includesimilar features (e.g. a horizontal drive mechanism, a controlmechanism, sensors) and an internal grasping mechanism 1620 whichincludes a vertical drive mechanism defined by one or more verticaldrive elements 1630, where the grasping mechanism is located within thedrive unit body 1602.

Features of the grasping mechanism 1620 may be similar to graspingmechanisms discussed above, including, e.g., a drive element 1630 withone or more contact elements 1632; gripping elements 1622 a,b alsoemploying contact elements 1624 a,b; and actuators 1626 a,b. Theactuators 1626 a,b can translate the gripping elements 1622 a,b to causethe grasping mechanism 1620 to securely grip a vertical element.

For internally positioned grasping mechanisms such as grasping mechanism1620 shown in FIG. 16, rotating mechanisms similar to those describedabove with reference to FIG. 14 may be employed (i.e., rotating contactelements or alternating sets of contact elements). FIG. 17 illustrates afifth mode 1700 of moving a drive unit 1600 onto an upper level 1702 ofan inventory management facility where the drive unit employs aninternal grasping mechanism 1620, in accordance with embodiments. Inthis mode 1700, the drive unit 1600 is connected with a vertical element1704 by the grasping mechanism 1620. In a first configuration 1700 a,the drive unit 1600 is capable to ascending or descending the verticalelement 1704 while clearing the upper level 1704. When the drive unit1600 is above the upper level 1704, the grasping mechanism 1620 canadjust to a rotating configuration (see FIG. 14), allowing the driveunit 1600 to rotate around the vertical element 1704 until positioned inthe second configuration 1700 b above the upper level 1702.

According to some embodiments, drive units can employ aspects of bothinternal and mechanical-arm-based grasping elements. FIG. 18 shows athird example of a vertically mobile drive unit 1800 with an alternativeinternal vertical element grasping mechanism 1820, wherein the graspingmechanism is internal to an articulating portion 1804 of the drive unitbody 1802. The articulating portion 1804 may be generally connected withthe body 1802, but have a pivotal connection 1808 attaching thearticulating portion with a protrusion 1806 of the drive unit body 1806.The drive unit 1800 can rotate around a vertical element by, e.g.,causing the grasping mechanism 1820 to rotate the drive unit in a mannersimilar to that shown in FIG. 17.

FIG. 19 illustrates a sixth mode 1900 of moving a drive unit 1800 ontoan upper level 1902 of an inventory management facility, in accordancewith embodiments. The drive unit 1800 is attached with a verticalelement 1904 by way of the grasping mechanism 1820. In a firstconfiguration 1900 a, the drive unit 1800 clears the upper level 1902,allowing it to ascend and descend the vertical element 1904 whileclearing the upper level 1902. The drive unit 1800 can actuate thearticulating portion 1804 away from the drive unit 1800 around thepivotal connection 1808, causing the drive unit to rotate to a secondconfiguration 1900 b, in which the drive unit 1800 is positioned abovethe second level 1902 and capable of disengaging the grasping mechanism1820.

Embodiments of grasping mechanisms herein described generally includeboth vertical drive mechanisms employing contact elements and grippingelements, also including contact elements. Contact elements may includevarious constructions, as discussed above; and contact elements forvertical drive mechanisms and for gripping elements may be the same ormay be different.

FIGS. 20-23 show various embodiments of drive mechanisms (2000, 2100,2200, 2300), for respective vertical element grasping mechanisms inaccordance with embodiments. For example, FIG. 20 shows an example of avertical drive mechanism 2000 for use with a vertical element 2002 thatincludes contact elements 2006 having a gripping surface, such as rubberor a durable adhesive, which allows the contact elements to firmly gripthe vertical element due to friction. The contact elements 2006 arepositioned within a casing 1004 containing an actuator 2010 that isoperable to turn the contact elements 2006 in order to impart force onthe vertical element 2002.

FIG. 21 shows a comparable vertical drive element 2100 for use with avertical element 2102 having a surface texture or grooved surface 2104.The vertical drive mechanism 2100 employs a first, geared or texturedcontact element 2108 which interacts with the surface 2104 of thevertical element 2102. Additional contact elements (e.g. contact element2110) may or may not employ a surface texture or grooved surface aswell. The contact elements 2108, 2110 are positioned within a casing2104 containing an actuator 2010 that is operable to turn the contactelement 2108 in order to impart force on the vertical element 2102. Insome cases, the actuator 2010 may further include a ratcheting mechanismthat interacts with the first contact element 2108 and provides for afail-safe mechanism by, allowing the vertical drive mechanism 2100 toautomatically hold position when not under power.

FIG. 22 shows a vertical drive mechanism 2200 for use with a verticalelement 2202 that operates by linear induction. The vertical drivemechanism 2200 includes contact elements 2206 that contact the verticalelement 2202 to control an orientation of the vertical drive mechanismwith respect to the vertical element. The contact elements 2206 arepartially enclosed in a casing 2206 which can also enclose a linearinduction actuator 2210. In alternative embodiments, the linearinduction actuator 2210 may include multiple components positioned inthe vertical drive mechanism 2200 around a circumference of the verticalelement 2202. The linear induction actuator 2210 is operable to impartforce on the vertical element 2202 from the vertical drive mechanism2200.

FIG. 23 shows an example of a grasping mechanism 2300 including avertical drive mechanism 2320 for use with a vertical element 3202having a complex shape, e.g. an I-beam. The grasping mechanism 2300includes rigid body 2334 supporting a drive element 2330 with one ormore contact elements 2332 and additional gripping/contact elements 2334a,b attached with the rigid body by actuators 2326 a,b. In operation,the grasping mechanism 2300 grasps a working portion 2304 of thevertical element 3203 by encompassing the working portion and moving thecontact elements 2334 a,b by the actuators 2326 a,b, in order to bringall contact elements 2332, 2334 a,b into contact with the workingportion. The grasping mechanism 2300 may connect with a drive unit via amechanical arm 2322, or other suitable connection.

Embodiments described above include drive units capable of transitingalong vertical elements to transfer resources between different floorsin an inventory system. In general, embodiments above provide forapparatuses, methods, and systems for allowing such drive units tonavigate between vertical elements and upper levels of multi-levelinventory management facilities where the vertical elements and upperlevels are stationary with respect to each other. However, according tovarious embodiments, drive units can transit to and from upper levels ofmulti-level facilities at least in part facilitated by movable panels inthe inventory system.

For example, FIG. 24 illustrates an example system 2400 for controllinga drive unit 2410 to transit onto an upper level 2404 of an inventorymanagement facility by way of a movable panel 2406, in accordance withembodiments. In a first configuration 2400 a, a drive unit 2410 cantransit along a first floor 2402 to a vertical element 2412 that extendsupward adjacent to a second floor 2404. As the drive unit 2410 ascendsthe vertical element 2412, a sensor 2430 can detect the presence of thedrive unit 2410 and cause a movable panel 2406 to move from a first,closed position 2406 to a second, open position 2406 b.

According to some embodiments, the movable panel 2406 is a single panelpivotally connected with the second level 2404. According to variousalternative embodiments, multiple panels can take the place of themovable panel. According to some alternative embodiments, the movablepanel 2406 can include a gap or void therein 2440 that allows themovable panel to close around the vertical element 2440. In such cases,the movable panel 2406 may be positioned interior to the second levelrather than at an edge of the second level.

At a second configuration 2400 b, the drive unit 2410 can ascend apredetermined distance above the second level 2404 such that the driveunit clears the open movable panel 2406 b. The open movable panel 2406 bcan then close beneath the drive unit 2410 in order to provide aplatform for the drive unit as shown in the third configuration 2400 c.In some embodiments, the drive unit 2410 can ascend until it triggers asecond sensor 2432 that causes the open movable panel 2406 b to close.

In order to descend from the second floor to the first floor, the driveunit 2410 can proceed in reverse by, e.g., by approaching and graspingthe vertical element 2410 as shown in the third configuration 2400 c; byascending above the movable panel 2406 to trigger the second sensor2432, causing the movable panel 2406 to open; and then descendingthrough a transitable open space formed by the open panel 2406 b. Whenthe drive unit 2410 passes the first sensor 2430, the first sensor cantrigger the open movable panel 2406 to close.

According to some embodiments, a movable panel can be opened or closedusing mechanical means. To that end, FIG. 25 illustrates a secondexample system 2500 for controlling a drive unit 2510 to transit onto anupper level 2504 of an inventory management facility by way of a movablepanel 2506, in accordance with embodiments. In an initial configuration2500 a, a drive unit 2510 can transit along a first floor 2502 to graspa vertical element 2512 by a grasping mechanism 2520. The drive unit2510 can then ascend along the vertical element 2512 until it encountersa movable panel 2506 in a closed position 2506 a.

The drive unit 2510 can then interact mechanically with the movablepanel 2506 in a second configuration 2500 b by mechanically displacingthe movable panel. In some cases, this process may be simplified by anelastic mechanism 2514 conferring a biasing force on the movable panel2506 which may reduce the force required to lift the movable panel. Inalternative embodiments, a biasing force may be generated by anactuator, by a counterweight system, or any other suitable means. Oncethe drive unit 2510 has cleared the movable panel 2506, as in the thirdconfiguration 2500 c, the movable panel can return to its initial,closed position 2506 a.

Comparable systems can employ a mechanical linkage (e.g., linkage 2516)to provide a mechanical means for a drive unit to actuate a movablepanel in order to descend. For example, FIG. 26 illustrates an examplesystem 2600 for controlling a drive unit to transit from an upper level2504 to a lower level 2502 of an inventory management facility by way ofa movable panel 2506, in accordance with embodiments. In a firstconfiguration 2600 a, the drive unit 2510 can approach the verticalelement 2512 along the second level 2504, and then grasp the verticalelement 2512 by the grasping mechanism 2520. The drive unit 2510 canalso interact with the linkage 2616, such that the drive unit 2510mechanically interferes with the linkage as it ascends along thevertical element 2512, and as shown in a second configuration 2600 b.After the drive unit 2510 has cleared movable panel 2506, the drive unit2510 can disengage from the linkage 2616 and descend past the movablepanel before it closes in order to return to the lower level 2502.

According to some embodiments, a drive unit may not be required todisengage from a vertical element to offload a resource. FIG. 27illustrates one such an example system 2700 for controlling a drive unit2710 to transfer a resource 2730 to an upper level 2702 of an inventorymanagement facility, in accordance with embodiments. In a firstconfiguration 2700, the drive unit 2710 can transit to a verticalelement 2712 and then grasp the vertical element by a grasping mechanism2720. The drive unit includes a resource platform 2708 operable to loador unload a resource 2730. The drive unit can then ascend or descendalong the vertical element 2112. As shown in a second configuration 2700b, the drive unit can ascend to a second level 2704 that includes areceiving mechanism 2702 for receiving the resource 2730. Here, thedrive unit 2710 can offload the resource 2730 to the receiving mechanism2702 without having to disengage from the vertical element 1712. Thereceiving mechanism 2702 can include any suitable means for receiving aresource including, but not limited to, a receiving platform, a chute, aconveyor, or the like.

FIG. 28 illustrates a block diagram of an example system 2800 forcontrolling a drive unit with vertical element transit capability in aninventory system, in accordance with embodiments. The system 2800 may beoperable to control any suitable drive unit with vertical transitcapability such as drive unit 103 shown in FIG. 1, or drive units 700,1600, or 1800 as shown in FIGS. 7-9, 16, and 18.

For example, the onboard control element 2804 can include any or all of,or any suitable combination of the following modules: a networkcommunication module 2806, a vertical movement control module 2808, adrive element module 2810, a retention management module 2812, apathfinding module 2814, a location sensing module 2816, an onboard datainput/output (I/O) module 2818, an onboard instruction buffer 2820 whichcan include an onboard data storage device, and an on board processingmodule 2822 for enabling operation of and/or communication between anyof the above modules. Any or all of said modules may be configured toenable automated or semiautonomous actions by a vertically mobile driveunit based on high-level instructions received from an inventory systemmanagement component such as the inventory system management element 109(see also FIG. 1). The onboard control element 2804 can include acomputer system configured to receive instructions via a network andcause a vertically mobile drive unit to act in accordance with thoseinstructions. The onboard control element 2804 can be configured as acentralized component in communication with other components of thedrive unit; or in alternative embodiments, the onboard control element2804 can include parts distributed and/or collocated among one or moreof the other components.

The modules making up the onboard control element 2804 can each executeinstructions at corresponding components of a vertically mobile driveunit, which can include at least the following components andsubsystems: a vertical movement subsystem 2824 (which can control avertical drive mechanism), a drive element subsystem 2826 forcontrolling a horizontal drive mechanism, a retention subsystem 2828 forcontrolling a resource retention element, a sensor subsystem 2830, andan onboard I/O device 1032. The vertical movement subsystem 2824 caninstruct a vertical element grasping mechanism to grasp or release avertical element; can instruct a rotating mechanism to cause rotation ofa drive unit around a vertical element; and can cause a vertical drivemechanism to engage a vertical element and exert force to ascend ordescend the drive unit. The retention subsystem 2828 can instruct aretention element to retain or to release a resource and/or a detect aweight of a currently retained resource. The sensor subsystem 2830 cancommunicate, for example, data obtained via sensors such as images,scanned information from a visual scanner or other scanner, or any othersuitable sensed information concerning the environment; and can receiveinstructions to use the sensor subsystem to scan particular locations oritems, to adjust a direction of a sensor such as a camera, to adjust again of any suitable sensor, or other suitable instructions forcontrolling the sensor subsystem. The onboard I/O device 2832 caninclude, for example, a switch, keyboard, screen, touchscreen,microphone, or any other suitable device for entering a user input atthe drive unit or for displaying a visual or audible output. Data caninclude, for example, instructions from a user to override a preexistinginstruction, such as: a “stop” instruction for causing the drive unit tohold station rather than continue in a programmed path; a “shutoff”instruction for causing the drive unit to power down and land; a “softshutoff” instruction for causing the drive unit to return to an originlocation and power down; a “return to base” instruction for causing thedrive unit to return to a particular location, such as a maintenance bayfor troubleshooting the drive unit or an inventory station fortroubleshooting an inventory management error; or any other suitableinstruction. Data can also include a status message, such as: an “intransit” message; a “waiting” message; a “busy” message; any suitableerror message; or any other suitable message or status identifier.

The onboard control element 2804 can send and receive networkcommunications via a network 2850 to and/or from the inventory systemmanagement element 2802 (see also FIG. 1). The inventory systemmanagement element 2802 can include an instruction buffer 2860, whichcan include memory and/or a data storage device for storing executableinstructions, and a processing module 2862. A remote I/O device 2840 canalso send and receive remote input/output data 2842 to the inventorysystem management element 2802 directly, to the inventory systemmanagement element via the network 2850, and/or to the onboard controlelement 2804 via the network. Remote input/output data 2842 can include,for example: a data flow for remote control via a remote device;instructions to retrieve or to transport an item; or any other suitableinstruction.

The inventory system management element 2802 can communicateinstructions via the network 2850 to the drive unit by transmitting theinstructions to the onboard control element 2804, where they can beprocessed by the onboard processing module 2822 and/or stored in theonboard instruction buffer 2820 for access by the onboard processingmodule. The instructions can be prepared at the processing module 2862of the inventory system management element 2802, and can also be storedtherein at the instruction buffer 2860. The multiple instruction bufferscan enable some degree of autonomy of the drive element separate fromthe inventory management system element 2802: for example, instructionsto retrieve a resource can be prepared at the processing module 2862 andstored in the instruction buffer 2869, and updated periodically to theonboard instruction buffer 2820; while the onboard processing module2822 can perform the instructions stored locally at the onboardinstruction buffer in the absence of overriding instructions from theinventory system management element 2802.

FIG. 29 illustrates an example process 2900 for controlling a drive unitto transfer a resource between a lower and upper level in an inventorysystem, in accordance with embodiments. Aspects of the process 2900 maybe performed, in some embodiments, by a similar system to the system2800 discussed with reference to FIG. 28. The system may be implementedby a vertically mobile drive unit such as those discussed in FIGS. 1, 7,16, and 18. Some exemplary inventory systems to which this process mayapply are described with reference to FIGS. 1 and 24-27.

In an embodiment, the process 2900 includes receiving instructions tomove a resource at an inventory management system (act 2902).Instructions can include a location of the resource and a resourceidentity, e.g. a surplus of a resource such as containers, packagingmaterial, totes; inventory items such as an individual inventory item, acontainer containing multiple inventory items, or an inventory holder,or comparable item. An origin and a destination of the resource aredetermined (act 2904). Next, the process 2900 includes selecting avertically mobile drive unit for retrieving the resource (act 2906). Theselection is based on, e.g. the origin and destination being ondifferent floors of an inventory management facility. Otherconsiderations for the selection may include whether the resourceexceeds a weight limit for the vertically mobile drive unit, as well asavailability of a drive unit; and when multiple drive units areavailable, proximity of an available drive unit to the origin location.

Next, the process 2900 includes the system determining a path for theselected drive unit, and instructing the selected drive unit to navigatethat path (act 2908). The path is determined based on, e.g., anysuitable combination of the current location of the drive unit, theorigin location, the location of a nearest available transitablevertical element in the facility, and a destination location. Generally,the path is determined to avoid collisions while minimizing a distanceor time of transit. The system then instructs the drive unit to proceedalong the path to the origin location of the resource (act 2909) toretrieve and retain the resource (act 2910), and then to proceed to,grasp, and ascend or descend the vertical element (act 2912) toward thefloor containing the destination location. The system can furtherinstruct the drive unit to disengage from the vertical element totransit along the destination level to the destination location to thedestination location (act 2913), and then release the resource at thedestination location (act 2914). The system can then release the driveunit to make it available for new instructions, which may includeproviding the drive unit with a holding pattern, a new destination, orother instructions (act 2916).

Specific process steps for ascending or descending to a second level inan inventory management facility are provided below with reference toFIGS. 30-35. Any number of these processes may be combined with aspectsof the process 2900 shown in FIG. 29. The various process stepsdescribed herein may be performed in conjunction with moving orretrieving a resource.

FIG. 30 illustrates a second example process 3000 for controlling adrive unit to transit between a lower and upper level in an inventorysystem, in accordance with embodiments. Aspects of the process 3000 maybe performed, in some embodiments, by a similar system to the system2800 discussed with reference to FIG. 28. The system may be implementedby a vertically mobile drive unit such as those discussed in FIGS. 1, 7,16, and 18. Exemplary inventory systems to which this process may applyare described with reference to FIG. 1.

In an embodiment, the process 3000 includes the system instructing adrive unit to grasp a vertical element at a side of the vertical elementhaving clearance to accommodate the drive unit 3002. For example, wherea vertical element abuts a destination floor, a drive unit thereon wouldtypically have transit clearance on a side of the vertical elementopposite the destination floor, or positioned at 90 degrees relative tothe destination floor. Next, the process 3000 includes the systeminstructing the drive unit to ascend beyond a height of the destinationfloor (act 3004), and then rotating about the vertical element until thedrive unit is positioned above the destination floor in suitableposition to disengage from the vertical element (act 3006). The systemcan then instruct the drive unit to descend to the destination floor,where the drive unit can disengage from the vertical element (act 3008).

FIG. 31 illustrates a third example process 3100 for controlling a driveunit to transit between a lower and upper level in an inventory system,in accordance with embodiments. Aspects of the process 3100 may beperformed, in some embodiments, by a similar system to the system 2800discussed with reference to FIG. 28. The system may be implemented by avertically mobile drive unit such as those discussed in FIGS. 1, 7, 16,and 18. Exemplary inventory systems to which this process may apply aredescribed with reference to FIG. 1.

In an embodiment, the process 3100 includes the system instructing adrive unit to grasp a vertical element on a side of the vertical elementhaving clearance to accommodate the dive unit, e.g. by a graspingelement connected with a body of the drive unit by a mechanical arm (act3102). Next, the process 3100 includes the system instructing the driveunit to ascend a predetermined distance above a height of thedestination floor (act 3104), and then extending the grasping elementarm away from the body of the drive unit, causing the drive unit torotate around and/or extend from the vertical element until the driveunit is above the destination floor (act 3106). The system can theninstruct the drive unit to descend to the destination floor, andoptionally detach the grasping mechanism from the vertical element andretract the mechanical arm when the drive unit is on the destinationfloor (act 3108).

FIG. 32 illustrates an example process 3200 for controlling a drive unitto ascend to an upper level of an inventory system via a movable panel,in accordance with embodiments. Aspects of the process 3200 may beperformed, in some embodiments, by a similar system to the system 2800discussed with reference to FIG. 28. The system may be implemented by avertically mobile drive unit such as those discussed in FIGS. 1, 7, 16,and 18. Exemplary inventory systems to which this process may apply aredescribed with reference to FIG. 24.

In an embodiment, the process 3200 includes the system instructing adrive unit to grasp a vertical element beneath a movable panel in adestination floor above the drive unit (act 3202). The system can theninstruct the drive unit to ascend through a transitable opening formedby the movable panel, while mechanically displacing the movable panel,and beyond a clearance height above the destination floor (act 3202).The system can then allow the movable panel to close, and furtherinstruct the drive unit to descend to the destination floor on top ofthe movable panel (act 3206).

FIG. 33 illustrates an example process 3300 for controlling a drive unitto descend from an upper level of an inventory system via a movablepanel, in accordance with embodiments. Aspects of the process 3300 maybe performed, in some embodiments, by a similar system to the system2800 discussed with reference to FIG. 28. The system may be implementedby a vertically mobile drive unit such as those discussed in FIGS. 1, 7,16, and 18. Exemplary inventory systems to which this process may applyare described with reference to FIG. 24.

In an embodiment, the process 3300 includes the system instructing thedrive unit to grasp a vertical element while the drive unit is above amovable panel in an origin floor above a destination floor (act 3302).The system can then instruct the drive unit to ascend the verticalelement by a predetermined distance above the origin floor, whileentraining the movable panel by way of a mechanical linkage in order toopen the movable panel (act 3304). Next, the process 3300 includes thesystem instructing the drive unit to transit through an opening formedby the open movable panel to the destination floor below (act 3306).

FIG. 34 illustrates a second example process 3400 for controlling adrive unit to ascend to an upper level of an inventory system via amovable panel, in accordance with embodiments. Aspects of the process3400 may be performed, in some embodiments, by a similar system to thesystem 2800 discussed with reference to FIG. 28. The system may beimplemented by a vertically mobile drive unit such as those discussed inFIGS. 1, 7, 16, and 18. Exemplary inventory systems to which thisprocess may apply are described with reference to FIG. 25.

In an embodiment, the process 3400 includes the system instructing adrive unit to grasp a vertical element, e.g. by a grasping mechanism,while the drive unit is beneath a movable panel in a destination floorthat is above the origin floor (act 3402). Next, the process 3400includes the system instructing the drive unit to ascend the verticalelement and trigger a sensor that causes the movable panel to open,creating a transitable opening in the destination floor (act 3402). Thedrive unit can then ascend through the opening and beyond a height ofthe destination floor (act 3406). In some embodiments, the system caninstruct the drive unit to sense, via a sensor of the drive unit or asensor positioned in the inventory system, a position of the destinationfloor (act 3407). This sensing can include, e.g., sensing an altitude orheight above a lower level; sensing a distance directly using anysuitable proximity sensing means including but not limited to: optical,IR, RFID, sonic, magnetic, or comparable sensing means; or detecting oneor more indications by a sensor of the drive unit, such as a markedindicia on a vertical element or on the destination floor or comparableindicator. In some cases, the drive unit can detect height by sensing adistance of travel. Optionally, the drive unit can further ascend totrigger a second sensor above the movable panel that causes the movablepanel to close, creating a platform that can support the drive unit.When the drive unit is positioned appropriately with respect to thedestination floor, e.g. as determined in the sensing step 3407, thedrive unit can be instructed by the system to descend to the destinationfloor (act 3408).

FIG. 35 illustrates a second example process 3500 for controlling adrive unit to descend from an upper level of an inventory system via amovable panel, in accordance with embodiments. Aspects of the process3500 may be performed, in some embodiments, by a similar system to thesystem 2800 discussed with reference to FIG. 28. The system may beimplemented by a vertically mobile drive unit such as those discussed inFIGS. 1, 7, 16, and 18. Exemplary inventory systems to which thisprocess may apply are described with reference to FIG. 26.

In an embodiment, the process 3500 includes the system instructing adrive unit to grasp a vertical element, e.g. by a grasping mechanism,while the drive unit is positioned on top of a movable panel in anorigin floor, the destination floor being below the origin floor (act3502). The drive unit can then ascend the vertical element to apredetermined height, where the drive unit can trigger a sensor thatcauses the movable panel to open, creating a transitable opening in theorigin floor below (act 3504). Next, the process includes the systeminstructing the drive unit to descend through the transitable opening tothe destination floor below (act 3506). Various processes discussedabove with respect to FIGS. 29-35 are suitable to controlling a driveunit to move between floors of an inventory system, or for movingresources between the floors of such systems. However, it will beunderstood that aspects of the above processes can also be employed torelocate unladen drive units for use in resource management on thedifferent floors.

FIG. 36 illustrates an example process 3600 for controlling a drive unitto reposition the drive unit in an inventory system, in accordance withembodiments. Aspects of the process 3600 may be performed, in someembodiments, by a similar system to the system 2800 discussed withreference to FIG. 28. The system may be implemented by a verticallymobile drive unit such as those discussed in FIGS. 1, 7, 16, and 18.Exemplary inventory systems to which this process may apply aredescribed with reference to FIG. 26.

In embodiments, the process 3600 includes the system instructing a driveunit to interact with resources on a first floor, e.g., by instructingthe drive unit to retrieve, translate, and release resources on thefirst floor; and subsequently to relocate to a second floor in order tointeract with resources on the second floor. For example, the system canreceive first instructions to move a first resource on a first floor ofan inventory system (act 3602). In this manner, the system can select adrive unit with vertical mobility based in part on the location of thefirst resource, the location of the drive unit, and the availability ofthe drive unit (act 3604). The drive unit is then used to move theresource, in similar manner to any suitable drive unit with a horizontaldrive element, such as the drive units described above with respect toFIGS. 2-5, including for such tasks as retrieving, translating, andreleasing heavy payloads like inventory holders, or for moving any otherresource in the inventory system (act 3606).

Next, the system can receive further instructions (or secondinstructions) to move a second resource on the second floor of theinventory facility (act 3608). Alternatively, the second instructionscan include instructions to relocate a drive unit to the second floor ofthe inventory facility from a different floor, e.g. in response todetecting a demand for additional drive units on the second floor, inresponse to detecting that a drive unit has left the second floor, or inresponse to a predicted future need for additional drive units. Thesystem can select the drive unit for relocation to the second floorbased on any of the above factors, and/or based on the availability ofthe drive unit, the degree of demand for additional drive units, theproximity of the drive unit to a suitable vertical element for use inrelocating to the second floor, or similar factor. The system theninstructs the selected drive unit to navigate to a suitable verticalelement and to ascend or descent to the second floor from the firstfloor (act 3612). Suitable methods for the ascent/descent and navigationto and from the vertical element are discussed above with respect toFIGS. 29-35.

Once on the second floor, the drive unit may be used immediately tointeract with resources on the second floor, or the drive unit may beheld in reserve pending new instructions. When the drive unit is neededimmediately, the system can instruct the selected drive unit to navigateto the location of the second resource on the second floor (act 3614)and then move the second resource from a third location to a fourthlocation on the second floor (act 3616). In some cases, aspects of thisprocess 3600 may be combined with aspects of the processes previouslydiscussed with respect to FIGS. 39-35. For example, in some cases, thesecond resource may be moved to a different floor from the second floor.Finally, the system can flag the drive unit as available for newinstructions (act 3618). In some cases, flagging the drive unit caninclude instructing the drive unit to assume a waiting pattern, e.g. bymoving to a waiting area, by returning the first floor, or by relocatingto a different floor with a greater demand for drive units.

FIG. 37 illustrates aspects of an example environment 3700 forimplementing aspects in accordance with various embodiments. As will beappreciated, although a Web-based environment is used for purposes ofexplanation, different environments may be used, as appropriate, toimplement various embodiments. The environment includes an electronicclient device 3702, which can include any appropriate device operable tosend and receive requests, messages, or information over an appropriatenetwork 3704 and convey information back to a user of the device.Examples of such client devices include personal computers, cell phones,handheld messaging devices, laptop computers, set-top boxes, personaldata assistants, electronic book readers, and the like. The network caninclude any appropriate network, including an intranet, the Internet, acellular network, a local area network or any other such network orcombination thereof. Components used for such a system can depend atleast in part upon the type of network and/or environment selected.Protocols and components for communicating via such a network are wellknown and will not be discussed herein in detail. Communication over thenetwork can be enabled by wired or wireless connections and combinationsthereof. In this example, the network includes the Internet, as theenvironment includes a Web server 3706 for receiving requests andserving content in response thereto, although for other networks analternative device serving a similar purpose could be used as would beapparent to one of ordinary skill in the art.

The illustrative environment includes at least one application server3708 and a data store 3710. It should be understood that there can beseveral application servers, layers, or other elements, processes orcomponents, which may be chained or otherwise configured, which caninteract to perform tasks such as obtaining data from an appropriatedata store. As used herein the term “data store” refers to any device orcombination of devices capable of storing, accessing, and retrievingdata, which may include any combination and number of data servers,databases, data storage devices and data storage media, in any standard,distributed or clustered environment. The application server can includeany appropriate hardware and software for integrating with the datastore as needed to execute aspects of one or more applications for theclient device, handling a majority of the data access and business logicfor an application. The application server provides access controlservices in cooperation with the data store and is able to generatecontent such as text, graphics, audio and/or video to be transferred tothe user, which may be served to the user by the Web server in the formof HyperText Markup Language (“HTML”), Extensible Markup Language(“XML”) or another appropriate structured language in this example. Thehandling of all requests and responses, as well as the delivery ofcontent between the client device 3702 and the application server 3708,can be handled by the Web server. It should be understood that the Weband application servers are not required and are merely examplecomponents, as structured code discussed herein can be executed on anyappropriate device or host machine as discussed elsewhere herein.

The data store 3710 can include several separate data tables, databasesor other data storage mechanisms and media for storing data relating toa particular aspect. For example, the data store illustrated includesmechanisms for storing information which can be used by modulesdescribed herein, such as resource scheduling information 3712, routeplanning information 3714, segment reservation information 3716, and/orinventory information 3718. It should be understood that there can bemany other aspects that may need to be stored in the data store, such asfor page image information and to access right information, which can bestored in any of the above listed mechanisms as appropriate or inadditional mechanisms in the data store 3710. The data store 3710 isoperable, through logic associated therewith, to receive instructionsfrom the application server 3708 and obtain, update or otherwise processdata in response thereto.

Each server typically will include an operating system that providesexecutable program instructions for the general administration andoperation of that server and typically will include a computer-readablestorage medium (e.g., a hard disk, random access memory, read onlymemory, etc.) storing instructions that, when executed by a processor ofthe server, allow the server to perform its intended functions. Suitableimplementations for the operating system and general functionality ofthe servers are known or commercially available and are readilyimplemented by persons having ordinary skill in the art, particularly inlight of the disclosure herein.

The environment in one embodiment is a distributed computing environmentutilizing several computer systems and components that areinterconnected via communication links, using one or more computernetworks or direct connections. However, it will be appreciated by thoseof ordinary skill in the art that such a system could operate equallywell in a system having fewer or a greater number of components than areillustrated in FIG. 37. Thus, the depiction of the system 3700 in FIG.37 should be taken as being illustrative in nature and not limiting tothe scope of the disclosure.

The various embodiments further can be implemented in a wide variety ofoperating environments, which in some cases can include one or more usercomputers, computing devices or processing devices which can be used tooperate any of a number of applications. User or client devices caninclude any of a number of general purpose personal computers, such asdesktop or laptop computers running a standard operating system, as wellas cellular, wireless and handheld devices running mobile software andcapable of supporting a number of networking and messaging protocols.Such a system also can include a number of workstations running any of avariety of commercially-available operating systems and other knownapplications for purposes such as development and database management.These devices also can include other electronic devices, such as dummyterminals, thin-clients, gaming systems and other devices capable ofcommunicating via a network.

Most embodiments utilize at least one network that would be familiar tothose skilled in the art for supporting communications using any of avariety of commercially-available protocols, such as TransmissionControl Protocol/Internet Protocol (“TCP/IP”), Open SystemInterconnection (“OSI”), File Transfer Protocol (“FTP”), Universal Plugand Play (“UpnP”), Network File System (“NFS”), Common Internet FileSystem (“CIFS”) and AppleTalk. The network can be, for example, a localarea network, a wide-area network, a virtual private network, theInternet, an intranet, an extranet, a public switched telephone network,an infrared network, a wireless network, and/or any combination thereof.

In embodiments utilizing a Web server, the Web server can run any of avariety of server or mid-tier applications, including Hypertext TransferProtocol (“HTTP”) servers, FTP servers, Common Gateway Interface (“CGI”)servers, data servers, Java servers and business application servers.The server(s) also may be capable of executing programs or scripts inresponse requests from user devices, such as by executing one or moreWeb applications that may be implemented as one or more scripts orprograms written in any programming language, such as Java®, C, C# orC++, or any scripting language, such as Perl, Python or TCL, as well ascombinations thereof. The server(s) may also include database servers,including without limitation those commercially available from Oracle®,Microsoft®, Sybase®, and IBM®.

The environment can include a variety of data stores and other memoryand storage media as discussed above. These can reside in a variety oflocations, such as on a storage medium local to (and/or resident in) oneor more of the computers or remote from any or all of the computersacross the network. In a particular set of embodiments, the informationmay reside in a storage-area network (“SAN”) familiar to those skilledin the art. Similarly, any necessary files for performing the functionsattributed to the computers, servers or other network devices may bestored locally and/or remotely, as appropriate. Where a system includescomputerized devices, each such device can include hardware elementsthat may be electrically coupled via a bus, the elements including, forexample, at least one central processing unit (“CPU”), at least oneinput device (e.g., a mouse, keyboard, controller, touch screen orkeypad) and at least one output device (e.g., a display device, printeror speaker). Such a system may also include one or more storage devices,such as disk drives, optical storage devices and solid-state storagedevices such as random access memory (“RAM”) or read-only memory(“ROM”), as well as removable media devices, memory cards, flash cards,etc.

Such devices also can include a computer-readable storage media reader,a communications device (e.g., a modem, a network card (wireless orwired), an infrared communication device, etc.) and working memory asdescribed above. The computer-readable storage media reader can beconnected with, or configured to receive, a computer-readable storagemedium, representing remote, local, fixed, and/or removable storagedevices as well as storage media for temporarily and/or more permanentlycontaining, storing, transmitting, and retrieving computer-readableinformation. The system and various devices also typically will includea number of software applications, modules, services or other elementslocated within at least one working memory device, including anoperating system and application programs, such as a client applicationor Web browser. It should be appreciated that alternate embodiments mayhave numerous variations from that described above. For example,customized hardware might also be used and/or particular elements mightbe implemented in hardware, software (including portable software, suchas applets) or both. Further, connection to other computing devices suchas network input/output devices may be employed.

Storage media and computer readable media for containing code, orportions of code, can include any appropriate media known or used in theart, including storage media and communication media, such as but notlimited to volatile and non-volatile, removable and non-removable mediaimplemented in any method or technology for storage and/or transmissionof information such as computer readable instructions, data structures,program modules or other data, including RAM, ROM, Electrically ErasableProgrammable Read-Only Memory (“EEPROM”), flash memory or other memorytechnology, Compact Disc Read-Only Memory (“CD-ROM”), digital versatiledisk (DVD) or other optical storage, magnetic cassettes, magnetic tape,magnetic disk storage or other magnetic storage devices or any othermedium which can be used to store the desired information and which canbe accessed by the a system device. Based at least in part on thedisclosure and teachings provided herein, a person of ordinary skill inthe art will appreciate other ways and/or methods to implement thevarious embodiments.

The specification and drawings are, accordingly, to be regarded in anillustrative rather than a restrictive sense. It will, however, beevident that various modifications and changes may be made thereuntowithout departing from the broader spirit and scope of the disclosure asset forth in the claims.

Other variations are within the spirit of the present disclosure. Thus,while the disclosed techniques are susceptible to various modificationsand alternative constructions, certain illustrated embodiments thereofare shown in the drawings and have been described above in detail. Itshould be understood, however, that there is no intention to limit theinvention to the specific form or forms disclosed, but on the contrary,the intention is to cover all modifications, alternative constructionsand equivalents falling within the spirit and scope of the invention, asdefined in the appended claims.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the disclosed embodiments (especially in thecontext of the following claims) are to be construed to cover both thesingular and the plural, unless otherwise indicated herein or clearlycontradicted by context. The terms “comprising,” “having,” “including,”and “containing” are to be construed as open-ended terms (i.e., meaning“including, but not limited to,”) unless otherwise noted. The term“connected” is to be construed as partly or wholly contained within,attached to, or joined together, even if there is something intervening.Recitation of ranges of values herein are merely intended to serve as ashorthand method of referring individually to each separate valuefalling within the range, unless otherwise indicated herein and eachseparate value is incorporated into the specification as if it wereindividually recited herein. All methods described herein can beperformed in any suitable order unless otherwise indicated herein orotherwise clearly contradicted by context. The use of any and allexamples, or exemplary language (e.g., “such as”) provided herein, isintended merely to better illuminate embodiments of the invention anddoes not pose a limitation on the scope of the invention unlessotherwise claimed. No language in the specification should be construedas indicating any non-claimed element as essential to the practice ofthe invention.

Preferred embodiments of this disclosure are described herein, includingthe best mode known to the inventors for carrying out the invention.Variations of those preferred embodiments may become apparent to thoseof ordinary skill in the art upon reading the foregoing description. Theinventors expect skilled artisans to employ such variations asappropriate and the inventors intend for the invention to be practicedotherwise than as specifically described herein. Accordingly, thisinvention includes all modifications and equivalents of the subjectmatter recited in the claims appended hereto as permitted by applicablelaw. Moreover, any combination of the above-described elements in allpossible variations thereof is encompassed by the invention unlessotherwise indicated herein or otherwise clearly contradicted by context.

All references, including publications, patent applications and patents,cited herein are hereby incorporated by reference to the same extent asif each reference were individually and specifically indicated to beincorporated by reference and were set forth in its entirety herein.

What is claimed is:
 1. An inventory management system, comprising: aninventory system comprising: a first level; a second level above thefirst level; and a vertical element extending upward from the firstlevel and passing through or adjacent to the second level; a drive unitcomprising: a body; a horizontal drive mechanism connected with thebody; a vertical element grasping mechanism connected with the body; anda vertical drive mechanism connected with the vertical element graspingmechanism, wherein the vertical drive mechanism is operable to rotatewith respect to the drive unit; and a management component configuredwith executable instructions, in order to, at least; receive informationrelating to a resource in the inventory system; instruct the drive unitto retrieve the resource at a first location on the first level usingthe horizontal drive mechanism; instruct the drive unit to grasp thevertical element with the vertical element grasping mechanism; instructthe drive unit to ascend the vertical element to the second level usingthe vertical drive mechanism; instruct the drive unit to rotate aroundthe vertical element by actuating the vertical drive mechanism; andinstruct the drive unit to move the resource to a second location on thesecond level.
 2. The inventory management system of claim 1, wherein:the drive unit comprises a robotic arm connected with the verticalelement grasping mechanism and pivotally connected with the body of thedrive unit; and wherein: instructing the drive unit to rotate around thevertical element comprises rotating the drive unit relative to thevertical element grasping mechanism by actuating the robotic arm.
 3. Theinventory management system of claim 1, wherein: the vertical drive unitcomprises a plurality of contact elements capable of being rotatedbetween a first, vertical orientation and a second orientation that istilted or horizontal; and wherein: instructing the drive unit to rotatearound the vertical element comprises: instructing the drive unit torotate the contact elements from the first orientation to the secondorientation; and instructing the drive unit to rotate around thevertical element in a helical or circular path by actuating the verticaldrive mechanism.
 4. The inventory management system of claim 1, wherein:the vertical drive unit comprises a plurality of contact elements, afirst subset of the contact elements being oriented vertically and asecond subset of the contact elements being oriented tilted orhorizontally; and wherein: instructing the drive unit to rotate aroundthe vertical element comprises: instructing the drive unit to bring thesecond subset of contact elements into contact with the verticalelement; instructing the drive unit to bring the first subset of contactelements out of contact with the vertical element; and instructing thedrive unit to rotate around the vertical element in a helical orcircular path by actuating the vertical drive mechanism.
 5. Acomputer-implemented method of managing a resource, comprising:selecting a drive unit from a plurality of drive units, each of thedrive units comprising a body, a horizontal drive mechanism connectedwith the body, a vertical element grasping mechanism connected with thebody, a vertical drive mechanism connected with the vertical elementgrasping mechanism, and a rotating mechanism connected with the verticalelement grasping mechanism; instructing the drive unit to transit afirst level of a multi-level facility using the horizontal drivemechanism to a vertical element; instructing the drive unit to grasp thevertical element by the vertical element grasping mechanism; instructingthe drive unit to ascend or descend to a second level in a multi-levelfacility using the vertical drive mechanism; instructing the drive unitto rotate around the vertical element via the rotating mechanism whilegrasping the vertical element to position the drive unit at leastpartially above the second level; and instructing the drive unit todetach from the vertical element while on the second level.
 6. Thecomputer-implemented method of claim 5, wherein the second level isabove the first level, and further comprising: instructing the driveunit to ascend past the second level using the vertical drive mechanism;instructing the drive unit to rotate around the vertical element usingthe rotating mechanism until the drive unit is at least partlypositioned above the second level; and instructing the drive unit todescend to the second level using the vertical drive mechanism prior todetaching from the vertical element.
 7. The computer-implemented methodof claim 6, further comprising: instructing the drive unit to rotatearound the vertical element away from the second level, via the rotatingmechanism, to create clearance for the drive unit to pass by the secondlevel.
 8. The computer-implemented method of claim 5, wherein:instructing the drive unit to rotate around the vertical elementcomprises: instructing the rotating mechanism to actuate a mechanicalarm connecting the vertical drive mechanism with a body of the driveunit, such that the body of the drive unit translates horizontallyaround the vertical element.
 9. The computer-implemented method of claim8, wherein: the mechanical arm has a first orientation operable toorient the drive unit nearer the vertical element and a secondorientation operable to orient the drive unit farther from the verticalelement; and actuating the mechanical arm causes the drive unit toextend away from the vertical element.
 10. The computer-implementedmethod of claim 5, wherein: instructing the drive unit to rotate aroundthe vertical element comprises: instructing the drive unit to rotate aset of contact elements attaching the drive unit to the vertical elementfrom a substantially vertical, first orientation to a second orientationthat is horizontal or tilted; and instructing the drive unit to rotatearound the vertical element in a circular or helical path by actuatingthe vertical drive mechanism.
 11. The computer-implemented method ofclaim 5, wherein: instructing the drive unit to rotate around thevertical element comprises: instructing the drive unit to extend a setof contact elements into contact with the vertical element in ahorizontal or tilted orientation; instructing the drive unit to rotatearound the vertical element in a circular or helical path by actuatingthe vertical drive mechanism.
 12. The computer-implemented method ofclaim 5, wherein: the second level is below the first level, and furthercomprising: instructing the drive unit to ascend above the first levelusing the vertical drive mechanism; instructing the drive unit to rotatearound the vertical element using the rotating mechanism until the driveunit is clear of the first level; and instructing the drive unit todescend past the first level using the vertical drive mechanism.
 13. Thecomputer-implemented method of claim 5, wherein instructing the driveunit to grasp the vertical element further comprises: instructing thedrive unit to extend a mechanical arm connecting the vertical drivemechanism with a body of the drive unit to bring the vertical drivemechanism into contact with the vertical element; and furthercomprising: instructing the drive unit to retract the mechanical arm tocause the drive unit to clear the first level.
 14. Thecomputer-implemented method of claim 5, further comprising: detecting,via a sensor, that the drive unit is positioned above a height of thesecond level prior to instructing the drive unit to rotate around thevertical element.
 15. The computer-implemented method of claim 5,further comprising: receiving information identifying a resource to beretrieved; instructing the drive unit to retrieve the resource from anorigin location on a first level of the multi-level facility using thehorizontal drive mechanism; and instructing the drive unit to move theresource to a destination location on the second level of themulti-level facility using the horizontal drive mechanism.
 16. Avertically mobile drive unit, comprising: a body; a horizontal drivemechanism connected with the body; a vertical element grasping mechanismconnected with the body and operable to grasp a vertical element; avertical drive mechanism connected with the vertical element graspingmechanism, the vertical drive mechanism being operable to cause thedrive unit to transit vertically along the vertical element; and arotating element connected with the vertical element grasping mechanismand operable to cause the drive unit to rotate around the verticalelement.
 17. The drive unit of claim 16, further comprising a roboticarm connected with the vertical element grasping mechanism and pivotablyconnected with the body of the drive unit by the rotating element, therobotic arm being configured to pivot away from the body of the driveunit from a first position to a second position via the rotating elementsuch that, when the vertical element grasping mechanism is connectedwith the vertical element and the robotic arm is moved from the firstposition to the second position, the body of the drive unit is partiallyrotated around the vertical element.
 18. The drive unit of claim 16,further comprising a robotic arm connected with the vertical elementgrasping mechanism and connected with the body of the drive unit, therobotic arm configured to extend from a first position to a secondposition such that, when the vertical element grasping mechanism isconnected with the vertical element and the robotic arm is extended fromthe first position to the second position, the body of the drive unit isdisplaced horizontally relative to the vertical element.
 19. The driveunit of claim 16, wherein the vertical drive mechanism comprises aplurality of contact elements capable of being rotated by the rotatingelement between a first, vertical orientation and a second orientationthat is tilted or horizontal, such that, when the vertical elementgrasping mechanism is connected with the vertical element and thecontact elements are in the first orientation, the vertical drivemechanism is operable to move the drive unit vertically along thevertical element, and when the contact elements are moved to the secondorientation, the vertical drive mechanism is operable to cause the driveunit to displace helically or circularly around the vertical element.20. The drive unit of claim 16, wherein the vertical drive mechanismcomprises a plurality of contact elements, a first subset of the contactelements being oriented vertically and a second subset of the contactelements being oriented tilted or horizontally, the first and secondsubsets being operable to independently contact the vertical element,such that, when the vertical element grasping mechanism is connectedwith the vertical element and the first subset of the contact elementsis in contact with the vertical element, the vertical drive mechanism isoperable to move the drive unit vertically along the vertical element,and when the second subset of the contact elements is in contact withthe vertical element, the vertical drive mechanism is operable to causethe drive unit to displace helically or circularly around the verticalelement.
 21. The drive unit of claim 16, wherein the vertical elementgrasping mechanism is positioned within a cavity in a body of the driveunit.
 22. The drive unit of claim 16, wherein the vertical elementgrasping mechanism comprises two or more locking features operable tolock the vertical element grasping mechanism into a locked position whenthe vertical element grasping mechanism is grasping the verticalelement.
 23. The drive unit of claim 16, further comprising a sensoroperable to detect a vertical position of the drive unit.